Complete guide to light therapy dosing

guide to dosing light therapy

Light therapy, Photobiomodulation, LLLT, phototherapy, infrared therapy, red light therapy and so on, are different names for similar things – applying light in the 600nm-1000nm range to the body. Many people swear by light therapy from LEDs, while others will use low level lasers. Whatever the light source, some people notice tremendous results, while others might not notice much at all.

The most common reason for this discrepancy is a lack of knowledge about dose. To be successful with light therapy, you first need to know how strong your light is (at different distances), and then how long to use it for.


What is the strength of my light?
How to calculate dose
More to learn

Medical & Healthcare Disclaimer
The information contained in this article is not intended or implicitly suggested to be an alternative for professional diagnoses, or profesionally recommended treatments & medical advice. Absolutely all of the content, including the article text itself, images, comments and other information, contained on this web page is for non-specific information purposes only. We strongly suggest that one should never ignore professional health/medical advice and we strongly suggest that one must not delay seeking a professionally recommended medical treatment because of information attained via reading this article/website. The products sold or recommended on this web site are absolutely not for the diagnosis, prevention, monitoring, treatment or alleviation of any specific disease, injury or disability.

How can I know the strength of my light?

The power density of light from any LED or laser therapy device can be tested with an ‘optical power sensor’ – a product that is usually sensitive to light in the 400nm – 1100nm range – giving a reading in mW/cm² or W/m² (100W/m² = 10mW/cm²). The sensor should be recently calibrated and set to the wavelength being emitted.

Power density? This is a measurement of how concentrated the light is at a given point (a.k.a. energy density, light power density, etc.). Specifically how many light photons are passing through a given area of space.

What do we use to measure our products? A Thorlabs S121C optical power sensor.

With an optical power sensor and a ruler, you can measure your light power density by distance. Below are the light power density readings of three of our products at different distances:

Infrared light Device Red Light Device Red/IR combo
Distance (cm) Power Density (mw/cm²) Power Density (mw/cm²) Power Density (mw/cm²)
0 1200 1100 1000
5 500 450 600
10 200 180 450
15 100 90 200
20 70 65 100
25 45 40 85
30 35 30 70
35 20 18 55
40 18 15 40

(Power densities over about 200mw/cm² are not typically indicated for skin treatment as they are quite powerful, however they can still be used for short periods to target deeper tissue. Power densities in the 500-1000+ range offer excellent penetration, useful for muscles, joints, brain tissue, etc.)

You can test any LED or laser to find out the power density at a given point. Full spectrum lights such as incandescents & heat lamps cannot be tested this way unfortunately because much of the output is not in the relevant range for light therapy, so the readings will be inflated. Lasers and LEDs give accurate readings because they only output wavelengths +/-20 of their stated wavelength.

The cheapest way to measure light intensity is with something called a ‘Solar power meter’. These are obviously intended for measuring sunlight, so not perfectly calibrated for measuring single wavelength LED light – the readings will be a ballpark figure, usually slightly higher than the actual. More accurate (and expensive) LED light meters such as the Thorlabs range are better.

Why do we use and recommend the Thorlabs sensors? These are the most common sensors seen in studies – this is what the researchers use. The aim of light therapy / photobiomodulation for most of us is to achieve similar positive results to those proven in scientific studies. It therefore makes the most sense to use the same light sensors as the people doing the studies – that way we are more closely following what works.

If you are using a solar power meter because they are cheaper, just consider that the measurement will be potentially inflated to some degree.

Optimal strength range

Once you have the readings of your device, you can determine the ‘light therapy range’ or the distance from which it needs to be applied to give an appropriate power density. This tends to be in the 10 – 200mW/cm² range. Vary the strength by varying the distance you apply light from.

Here is the therapy range of our Red Light Device for example:

red light device effective range
RLM Red Light Device showing range between 10cm & 35cm
infrared mini light therapy range
Therapy range of the infrared mini 830 device


How to calculate light therapy dose

Light therapy dose is calculated with this formula:

Power Density x Time = Dose

Fortunately, most recent studies use standardised units to describe their protocol:

  • Power Density in mW/cm² (milliwatts per centimeter squared)
  • Time in s (seconds)
  • Dose in J/cm² (Joules per centimeter squared)

For light therapy at home, power density is therefore the main thing you need to know – if you don’t know it, you won’t be able to know how long to apply your device for to achieve a certain dose. It is simply a measure of how strong the light intensity is (or how many photons are in an area of space).

With angled output LEDs, the light is spreading out as it moves, covering a wider and wider area. This means relative light intensity at any given point gets weaker as distance from source increases. Differences in beam angles on LEDs also affects the power density. For example a 3w/10° LED will project light power density further than a 3w/120° LED, which will project weaker light over a larger area.

Light therapy studies tend to use power densities of ~10mW/cm² up to a max ~200mW/cm².
Dose is simply telling you how long that power density was applied for. Higher light intensity means less application time is required:

5mW/cm² applied for 200 seconds gives 1J/cm².
20mW/cm² applied for 50 seconds gives 1J/cm².
100mW/cm² applied for 10 seconds gives 1J/cm².

These units of mW/cm² and seconds give a result in mJ/cm² – just multiply that by 0.001 to get in J/cm². The full formula, taking into account standard units is therefore:

Dose = Power Density x Time x 0.001

 What dose should I aim for?

dose-responseNow that you can calculate what dose you are getting, you need to know what dose is actually effective. Most review articles and educational material tends to claim a dose in the range of 0.1J/cm² to 6J/cm² is optimal for cells, with less doing nothing and much more cancelling out the benefits.

However, some studies find positive results in much higher ranges, such as 20J/cm², 70J/cm², and even as high as 700J/cm². It’s possible that a deeper systemic effect is seen at the higher doses, depending on how much energy is applied in total to the body. It could also be that the higher dose is effective because the light penetrates deeper. Getting a dose of 1J/cm² in the top layer of skin will only take seconds. Getting a dose of 1J/cm² in deep muscle tissue could take 1000 times as long, requiring 1000J/cm²+ on the skin above.

Distance of the light source is crucially important here, as it determines the light power density hitting the skin. For example, using the Red Light Device at 25cm instead of 10cm would increase the application time required but cover a larger area of skin. There’s nothing wrong with using it from further away, just be sure to compensate by increasing application time.

Calculating how long a session

Now you should know your light’s power density (varying by distance) and the dose you want. Use the formula below to calculate how many seconds you need to apply your light for:

Time = Dose ÷ (Power density x 0.001)

Time in seconds, dose in J/cm² and power density in mW/cm²

Is there more to light therapy dosing?

While the information laid out here is adequate to measure dose and calculate application time for general use, light therapy dosing is a much more complicated matter, scientifically.

  • J/cm² is how everyone measures dose now, however, the body is 3 dimensional. Dose can also be measured in J/cm³, which is how much energy is applied to a volume of cells, rather than just applied the surface area of skin.
  • Is J/cm² (or ³) even a good way to measure dose? A 1 J/cm² dose can be applied to 5cm² of skin, while the same 1 J/cm² dose could be applied to 50cm² of skin. The dose per area of skin is the same (1J & 1J) in each case, but the total energy applied (5J vs 50J) is vastly different, potentially leading to different systemic outcomes.
  • Different strengths of light can have different effects. We know that the following strength and time combinations give the same total dose, but the results wouldn’t necessarily be the same in studies:
    • 2mW/cm² x 500secs = 1J/cm²
    • 500mW/cm² x 2secs = 1J/cm²
  • Session frequency. How often should sessions of ideal doses be applied? This may be different for different issues. Somewhere between 2x per week and 14x per week is shown effective in studies.



Using the right dose is key to get the most out of light therapy. Higher doses are required to stimulate deeper tissue than for the skin. To calculate dose for yourself, with any device, you need to:

  • Figure out your light’s power density (in mW/cm²) by measuring it at different distances with an optical power sensor.
    • If you have one of our products, use the table above.
  • Calculate dose with the formula: Power Density x Time = Dose
  • Look for dosing protocols (strength, session time, dose, frequency) that have been proven effective in relevant light therapy studies.
    • For general use and maintenance, between 1 and 60J/cm² may be appropriate



  1. Is light-emitting diode phototherapy (LED-LLLT) really effective? WS Kim et al. 2011.
  2. Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. P Avci et al. ‎2013 .
  3. The growth of human scalp hair mediated by visible red light laser and LED sources in males. RJ Lanzafame. 2013.
  4. The growth of human scalp hair in females using visible red light laser and LED sources. RJ Lanzafame. 2014
  5. Low-level laser therapy in chronic autoimmune thyroiditis: a pilot study. DB Höfling et al. 2010.
  6. Low-level laser in the treatment of patients with hypothyroidism induced by chronic autoimmune thyroiditis: a randomized, placebo-controlled clinical trial. DB Höfling et al. 2013.
  7. Efficiency of low-level laser therapy in reducing pain induced by orthodontic forces. AA Bicakci. 2012.
  8. In Vitro effect of low-level laser therapy on typical oral microbial biofilms. FG Basso et al. 2011
  9. 830 nm light-emitting diode low level light therapy (LED-LLLT) enhances wound healing: a preliminary study. PK Min et al. 2013.
  10. Combination blue (415 nm) and red (633 nm) LED phototherapy in the treatment of mild to severe acne vulgaris. DJ Goldberg et al. 2006.
  11. Psychological benefits 2 and 4 weeks after a single treatment with near infrared light to the forehead: a pilot study of 10 patients with major depression and anxiety. F Schiffer et al. ‎2009.
  12. The effect of low-level laser therapy during orthodontic movement: a preliminary study. M Youssef et al. ‎2008.
  13. Does Phototherapy Enhance Skeletal Muscle Contractile Function and Postexercise Recovery? A Systematic Review. Borsa et al. 2013.
  14. Meta-Analysis of Pain Relief Effects by Laser Irradiation on Joint Areas. Ho Jang et al. 2012.

234 thoughts on “Complete guide to light therapy dosing

  1. Joshua Forter says:

    So are these daily recommendations? For example…for thyroid…I would use the IR 6+ minutes a day EVERYDAY? Thanks.

  2. Janis Bell says:

    Do you have any information on using the lights with arthritis? Guessing under joint pain, but it’s a little different as my husbands thumbs are all swollen and puffy too.

  3. Peter Martinez says:

    Very comprehensive yet informative breakdown. There is a lot of confusion about this topic out there. It’s nice to see someone package it for us so nicely. Thanks

        • Joe says:

          The question doesn’t make sense. 100mw/cm2 is the light intensity (at a specific distance) and would change depending on the distance.
          If you used the light from the exact distance that gives 100mW/cm2 light intensity, then anywhere from 10 seconds to several minutes is considered reasonable.

    • Joe says:

      My understanding is that the ideal wavelength for acne treatment is 415nm and that 415nm/blue only lights are somewhat effective. There seems to be a synergy between blue and red though, and combination lights/treatment are considered superior. It makes sense if you think about it – blue will kill bacteria, but also stress your cells – blue combined with red will still kill bacteria, but your cells will have protection. Red only lights have proven effectiveness against acne too. Infrared doesn’t seem as effective as red for acne.

      Blue-only –
      Red-only –
      Combination blue-red – &
      Combination blue-infrared –
      Blue-only vs. combination blue-red –

      • reuben says:

        doesnt our pc screen emit blue light that is very bad for the skin? is it the same blue light for acne treatment?

        • Joe says:

          It is a low level of blue light coming from your pc screen. It is mainly of interest for eye health, not the skin.
          I think red only light is the best long term option for acne treatment.

          • Jean says:

            Here is an add on your answer, – if you have one of the newer computer screens or like your phone, thay have what you call an automatic Red-eye or Blue Light cancellation app on it,… if not, there is a few good ones out there that are for free for download.

          • Julie Andras says:

            Blue light has been scientifically proven to kill bacteria and reduce the inflammation of acne vulgaris and other inflammatory conditions of the SKIN; even poison ivy.

          • Joe says:

            You could say the same about many harmful things. For example: X-Rays have been scientifically proven to kill bacteria and reduce the inflammation of acne vulgaris and other inflammatory conditions of the skin. X-Rays even used to be a standard acne treatment.
            Of course we now know that the long term risks from X-Ray treatment is not worth the short term benefits. The same applies to blue light treatment – you can reduce inflammation now but you’re just swapping it for rapid aging and DNA damage.

          • Rogier van der Heide says:

            “red only is the best for acne”? “red only” is what you sell. 415nm blue kills bacteria and reduces sebum production, and is the best for acne. We see that every day in the clinic.

          • Joe says:

            Simple as that, is it? We used to sell a blue light product too but stopped. We strongly recommend everyone stop using blue light.
            You know what used to be popular for acne treatment up until the 1960s?
            Back in our grandparents and great grandparent’s generations, if someone had acne, they would go to ask the doctor, and most doctors would have their own in-house X-ray machine. Give the face a quick blast, repeat over multiple sessions and the acne bacteria are sterilised and the acne lesions are lessened and gone. Sebum production down, etc. Maybe the acne could be back later, but job done for now. The doctors of that generation would likely say ‘X-ray treatment is best for acne, we see that every day in the clinic’.
            It was only after years and years that it became apparent that people were getting thyroid cancers, skin and bone cancers and so on.

            I just want to say that this is the same type of approach as using blue light for acne. It isn’t just killing the acne, with bright blue light treatments you are causing direct DNA damage in your own cells and mitochondria, perhaps not as destructively as X-Rays, but in the same way you are harming yourself in the long term to get a short term aesthetic improvement.
            I would absolutely not use blue light on your body like that.
            Red only is the best for acne, in the mid to long term. Blue at 415nm will treat acne in the short term, at the expense of aging the person, harming the eyes and skin. Blue is not appropriate for use on the face, just as X-rays aren’t.

            So blue light kills acne but harms you too. Most of the acne bacteria or fungal cells might be dead for now, but with blue light therapy, your skin is permanently weaker and so it’s more likely to come back, and come back worse, plus you’ve aged yourself with the treatment. You could be setting up the skin for even worse problems.

    • Joe says:

      It depends what dose you want to aim for. In studies on hair health I’ve seen 1.5J/cm² all the way up to 70J/cm² in studies.
      I do not suggest using it pressed right onto the scalp.

      • Beverly says:

        I need to know if tan center red light bed with 330 mn. Suggested daily 15 min sessions will give me all available health benefits..very cheap but need benefits

        • Joe says:

          Do you mean 630nm rather than 330nm?
          If so then it is a good wavelength according to studies. The ideal time for a session depends entirely on the power density (light intensity) hitting your skin, so I can’t say if 15 minutes is a good session in that tan center bed.

  4. Diego says:

    Great article!! I’ve read that red light can contributes too to photoaging, and there are some sunscreens that protect from this range too, like vitamin c based serums, is this correct?

    • Joe says:

      I do not believe so. According to the data I have seen, red is potentially protective against photoaging. Strong sources of longer infrared like heat lamps and sunlight might contribute to photoaging in large doses (via denaturing cellular proteins). For red to contribute to photoaging, you’d literally have to burn your skin with it. I don’t know about the vitamin C based serums, but I know sunscreen producers are looking for ways to block the longer infrared rays in addition to the UV.

  5. beth says:

    Anyone know where I can find the info on hz and nm for red light therapy lipo machines? Considering buying one but would like know more about how and why they work first.

  6. PK says:

    Can use red and blue LEDs that are designed for plants that are at the right wavelengths and calculate the dose using the formulas from your post.

    • Joe says:

      Blue LEDs will be problematic as they damage mitochondrial function. Otherwise though yes, as long as you know the power density at a certain distance you can calculate a dose.

  7. PK says:

    Can I use a Lux meter instead of a solar power meter and convert to W/CM2? I can get an app for my iPhone and do this. I know that the iPhone has an IR filter but the specs say it is set for a 800nm cutoff.

    • Joe says:

      I’m not sure about that. If you can get a reading that seems reasonable then go for it. Any sort of measure of light intensity would work, provided you can convert it to mW/cm2 (and you know the wavelengths are in the 600-950nm range only). Lux is mainly for measuring white visible light, so it won’t necessarily show any reading for infrared units.

      • Tony says:

        Joe, reference to you comment on. lux reading devices for sale in the UK only seem to read in lux. As I have the same problem my device has an output of 500w yet 8 months later trying to follow guidelines on doses I see and feel no benefits. So I need to actually measure my device for output and Compare it to w/cm they say it actually does. Any thoughts, thanks

    • kelly says:

      What app are you using? (And have your indeed found it suffices for the purpose of measuring the light for determining potential bio-therapeutic effects?

    • Jean says:

      There is no exact conversion factor.
      The problem is that lux and mW/cm^2 are not simply different units, rather they are units for different measurements.
      mW/cm^2 is a unit for irradiance (energy falling on a surface) and lux is a photometric unit for illuminance (visible light falling on a surface).

  8. William says:

    I’ve been experimenting with placing the infrared and ref light very close to my mouth (~2 inches) for a minute or two, to give my teeth through the gums a good dose.

    How long do you think it would take for the skin or eyes to be hurt from heat damage at this distance?

    • Joe says:

      Hi James,
      I don’t know if there are any good human studies to conclude a dose recommendation for that. Keeping it low to avoid any heating is important.

  9. Julia says:

    In your last table (“Doses shown to be effective in different areas”) you list columns for RED LIGHT DEVICE at 10CM and INFRARED LIGHT DEVICE at 0CM
    However, in the chart for power density at various distances, it lists that only the RED/IR COMBO can be used at 0CM – both the RED LIGHT and INFRARED LIGHT devices list they are “out of the therapy range” (too strong) at 0 or 5 cm – please clarify if the column for that last table (doses shown to be effective) at 0CM is actually meant to be the RED/IR COMBO at 0CM

    I am considering buying your product but want to know what I’m looking at in these dose tables.

    • Joe says:

      Hi Julia,
      That table was out of date. I forgot to update it. The combo light and the infrared light models have changed since then. I have updated the tables for you now.

  10. Anthony says:

    Do you have Power Density vs Distance data for the Mini Devices? This would help determine the dose applied. Also, is there a solar power meter that you could recommend?

    • Joe says:

      Hi Anthony, I will add some charts for the mini devices.
      For the solar power meter, the Tenmars brand/range works well. Just be sure to get one that measures up to 200mW/cm² (2000W/m²) or higher.

  11. Ralph says:

    Could someone explain this to me: I don’t understand the dose. It is quoted from the study in your note n.4 on hairloss.

    “Patients treated at home every other day × 16 weeks (60 treatments, 67 J/cm2 irradiance/25 minute treatment, 2.9 J dose)”,

    Is it 2,9J per session of 25 minutes?
    or It is 67J per session of 25 minutes?

    I need help for that. Something is not clear in the equation.

    • Joe says:

      Hey Ralph, yeah this is a common issue between studies – that studies don’t use all the same descriptors for the same thing. The total energy applied is measured in ‘J’, but it’s not very useful because you don’t know over how large an area that is applied.
      The J/cm2 measurement is what you need to look at and that’s what I would consider to be the dose. So they are applying a 67 J/cm2 dose over 25 minutes. Use the formulas above and that gives the power density / light intensity hitting the skin is about 45 mW/cm2.

  12. Seppe says:

    Hi Joe, great info-page, nice work!
    I was wondering though if the energy-dose in J/cm² is the main effect-determining factor as you also claim that there is a limited effective power-density (mW/cm²) range for red/IR Phototherapy? As an example, can it be that the biological effect of day 1J/cm² is different between treatment A: 10mw/cm² x 100s and treatment B: 100mW/cm² x 10s? Parameters in both treatments are within the Low-Level Light Therapy acceptable range. In other words, is there evidence for other limiting factors (e.g. light-in tissue penetration depth or cellular photo-acceptor quantum yield) that could be important for determinig the optimal therapeutic power-density and irradiation time? In photodynamic therapy, this is the case (photosensitizer concentration, local oxygen availability & consumption rate). Thanks for sharing your view on this!

    • Joe says:

      Hey Seppe,
      Yes I think you are right. What we have laid out in this post is sort of the scientific consensus, but not the whole picture, and I think the standard guidelines for power density range and doses will change in future.
      I think there are different effects to different power densities, such as greater penetration potential.
      I don’t know if dose in J/cm² is the best way to determine effect and the effective dose does of course vary by individual depending on skin colour and other factors anyway.
      The J/cm² model doesn’t take into account the total energy input into the body which is think is significant.
      At the moment, I personally just tend to use red lights for the skin, (near)infrared for anything deeper. I tend to keep the light at a range of 100mW/cm² intensity or less for just a few minutes for general skin, and around 200mW/cm2 up to 10 mins or more for deeper issues. If I use them further away I will go up to 20 mins or more exposure, without really thinking about calculating a dose.

      • Seppe says:

        Dear Joe,
        Thank you for your ultrafast and honest reply. I beleive you are right and that the optimal doses are very variable between wavelengths, indications and the population. Luckily there is a broad effective therapeutic window and there is actually nothing that can go wrong… Thanks!

  13. Halid Muhamad says:

    Hai, Joe.

    Do you have a PDF Version of this journal? I really need this article for my thesis as my reference. if you dont mind, please email it to me.

    thank you so much, joe.

  14. Todd says:

    Hello there,
    Will you have a chart for the Mini Devices? Very curious of how they compare to the higher priced COB devices with cooling fans. Will the Red Light Mini 670 be enough for the testicles (from what I’ve read it appears to be so)? I’d like to minimize time spent with a device between my legs, but would like to save a little cash if the Mini is all I’ll need (overkill for higher power devices?). Can I press the Mini 670 directly against “my boys” or would having some distance make the light spread a little better (the COB may likely be less of a concern)? Seriously considering the new higher power COB Red Light Device for $199…the picture of it turned on seems to show a powerful “beam” with the new lens. I would like to see a “side by side” of how the two different lens of the Red Light Devices project. You seen to have an “older model” with a reflector and nothing showing the newer one (flatter lens) in use. I would love to see this. Maybe a “side by side” of all the Red Devices? Sorry for all the questions. Love your website and dedication to providing quality devices at affordable prices.

    • Joe says:

      Hi Todd,
      Thanks for the comments. The red mini devices would seem to be potentially sufficient for something like testicular light therapy. The power density by distance is mentioned on the product pages. It is usually better at long distances than the more powerful lights, just covers a smaller area.
      The larger devices are all still suitable too. They’re not overkill as such, they just cover a wider area, so you’ll be hitting the target area but also the skin nearby.

    • Joe says:

      I would not make a medical recommendation for anyone, but I will say it depends entirely on what light you’re using, or more specifically what power density of light is coming out of it. If you have 100mW/cm2 of light intensity, I would use it for at least 5 minutes throughout the day, you can go up to 30 minutes though. It’s best to experiment a bit.
      near-infrared light may be preferable to red if the candida is deeper inside the vagina, since near infrared penetrates well.

  15. Glenn says:

    Prior to finding your page I purchased a 135w ufo grow light which I have painstakingly replaced all of the 3w epileds with red leds of 630nm and 660nm. I am trying to work out the dosage for rosacea. I don’t have a power meter but have measured 3000 lumen’s @ 60cm and 30000 @ 30cm. I have been trying to convert to j/cm2 but not having any luck and chance you may be able to help?

    • Joe says:

      You can’t convert a light intensity measurement (lumens) to dose (J/cm2) directly, as dose is a measure of light intensity x time.
      First you need to figure out how to convert your lumens measurement into the appropriate light intensity measurement – mW/cm2. To do that, you need to know over what area that lumens measurement is. Is it lumens per meter, or lumens per centimeter, etc?
      It will be even more complicated though as the wavelength affects the conversion from lumens to other metrics. Lumens is a measure of white light mainly, not ideal for measuring narrowband red.
      UFO type lights have the LEDs quite widely spaced out. If the beam angle on your LEDs is over about 45 degrees, the power density is bound to be weak unless you press it close to the skin.

    • Joe says:

      I would not make a specific medical recommendation on something like that. For deeper tissue in general, I think a higher dose of near-infrared (more penetrative than red) may potentially be useful, as you are trying to target the deeper cells. I would suggest at least 60 J/cm2 but higher doses may be better.

  16. jim says:

    It is my understanding that you need an IR meter to properly measure IR light. Solar meters are calibrated for full spectrum sunlight. I am not sure that they are accurate for single wavelength red light either.

    • Joe says:

      Hi Jim,
      Sure, you are right. There is a degree of inaccuracy with those. If you need the best possible accuracy for a scientific study or something, there are more accurate meters to measure power density (although they are much more expensive). Something like a Thorlabs S121C or similar would be better for measuring the red and NIR wavelengths.

  17. Mod says:

    Hey Jon,

    I noticed the lamp heats up at 10 minutes. I am concerned about chemicals released in the air. Specifically, bromine. Do these lamps give off bromine?

  18. Mod says:

    Well, it is my understanding that when heat reacts with painted metal and plastic; bromine is released in ino the air. There is a metaly smell when the lamp heats up. I think I’ll use the infrared instead the led. Thank you so much Joe.

    • Joe says:

      The only part of the lamps that gets hot after a while is the unpainted aluminium heat sink inside. There are no hazardous chemicals involved in the paint or anywhere else on any products.

  19. Jan says:

    I like the combo full body product but will this be sufficient for targeted areas as in thyroid or say, thumb joint issues?

    • Joe says:

      Yes of course. To use it for any sort of deeper targeted issue you just need to use it from a closer distance.

  20. Shawna says:

    Hi I have recently started red light therapy at a tanning salon but I don’t trust that they even know what the wavelength is or the density or anything so I’m not sure if it’s even safe. They put the red bulbs in a lay down tanning bed so how do I know if I’m not too close etc.. or how long to go. I got a head ache after 20 mins which was my first time and I had to double up on towels on my eyes I’m extremely sensitive to the light but I really want the benefits now I’m confused ! Please help:)

    • Joe says:

      I wouldn’t expect your average salon to know much about wavelength or power density. There’s quite a steep learning curve on the technical aspects of light therapy. I’m not sure about the red bulbs used in those tanning beds. They don’t seem to be studied at all by researchers. It makes sense for now to stick with LEDs or low level lasers.
      Getting a headache after your first full body treatment isn’t necessarily a bad thing. It’s probably a sign that you had quite a lot of Nitric Oxide in your mitochondria, and it was all displaced into the blood. This would cause quite a bit of vasodilation of blood vessels and thus a headache. Next time it will be less severe or even gone.
      Your eyes will adjust to the bright red light after a few sessions. If you are very sensitive, you should use near infrared light on the face, rather than red (since near infrared is invisible and doesn’t overstimulate the eyes). You could use something like this for full body treatment – – having the near infrared panel in front of your face and the red panels on the body.

  21. oliviaclymer says:

    I am currently in red light therapy using the pods at the nearest clinic–the bulbs are 680 and 860. If I pick appliances here, should I just go with the closest wattage and expect the same effect if dosed properly? (I am getting that the bulbs being used in the pod are specific to that set up and not necessarily exactly what I’d need to do this at home…)

    • Joe says:

      Hi Olivia,
      Yes the effects should be similar if you have similar wavelengths, similar power and surface area coverage and use for a similar time.
      The wattage of a device isn’t important as such, but the power output measured in mW/cm2 is more important. The problem is that most traditional (non-LED) type bulbs are very inefficient electrically, so the stated watt consumption does not provide a good comparison.

  22. David says:

    Thank you for this extraordinarily helpful explanation of dosage and light therapy. I am working with a newly acquired red 660 nm led panel and I am trying to work out the power density. I have a PAR meter that reads 345 micro mols at 15cm. Using the formula 119.708/wavelength nm = watts square meter/micro mols/square meter/sec, I get 62.6 watts/ sq.meter. I then divide by 10,000 (1 sq.meter = 10,000 to get 6.26 milwatts per Is that correct? If not, would you please help me find what the correct answer is? Thanks for your help and for all the great information on your site. …david…

  23. Jana says:

    What is the concensus regarding the use of sunlight for light therapy? Direct sunlight is about 0.1 W/cm2 in full spectrum, with about 1/10 to 1/3 of that in the therapeutic wavelength bands. The typical therapeutic dose of 60 J/cm2 would thus be obtained in 2000-6000 seconds. So sitting next to the window for an hour should do it, right? The glass filters out most of the UV and is transparent to IR.

    • Joe says:

      Sunlight in the morning or evening is the best, with more of it being red/NIR. Strength of light otherwise depends on location and time of year.
      I think you can get about 30mW/cm2 of light intensity of the relevant wavelengths from midday sunlight in the southern USA in summer. Only about half of this will be really at/near the peak wavelengths. An even smaller amount will be the more penetrative near infrared wavelengths.
      It’s not the same either way though. The heating of the skin cells from sunlight can lead to photoaging over time. The relative lack of strength of near infrared around 800nm means deeper penetration won’t be possible with sunlight.
      On the plus side, sunlight has some other benefits from the UV.

  24. Sean says:

    For treatment times, if I did 100J/cm2 on the back, 60J on the head, 38J on the thyroid, and 50J on the chest, etc in one day, would this add up to an overdose (through blood) or because different areas where used it’d be okay?

    • Joe says:

      From what I have seen you can’t overdose through the blood. Using light therapy like you suggest is perhaps a good way to do it. ‘Overdosing’ is only a single cell issue, and only relevant to the top layer of skin cells in humans. The problem with it is mainly the inadvertent heat build-up, rather than any negative photon-tissue reaction, as skin cells (or sperm cells or other single cell) don’t function well over 46 degrees C.

  25. Sean says:

    Your graph says optimal for cells is 0.1-6J/cm2 and overdose is ~70J/cm2. So if you where to target, say the thyroid with 100J/cm2, wouldn’t you be overdosing the skin cells on top?

    • Joe says:

      Yes. There’s no avoiding the skin overdosing when targeting deeper tissue.
      You could split the 100J/cm2 dose throughout the day if you are particularly concerned. The negative effects of ‘overdosing’ is mainly down to the heat build-up over time in my opinion.

  26. Sean says:

    If your device is 200mW/cm2 @0cm and 20mW/cm2 @60cm then would 30cm = 110mW/cm2 or is it exponential so 30cm = ~50mW/cm2.

      • Eric says:

        What’s your function for calculating irradiance falloff? it’s something like
        Irradiance = 200mW/cm2 – xcm^n?

        I’m asking because I’m trying to figure out what distance I need to achieve 8mW/cm2 and 5mW/cm2

  27. Mary says:

    Hi there! I was wondering if you’d be able to help me figure this out as I’m not sure I know what I’m doing. A friend ordered this for me to use for anti aging purposes. Can you help me understand the proper dosing with this model? Many thanks in advance!

    Yescom 225 Red LEDs Grow Light Panel Hydroponics Indoor Garden Room Tent Ultrathin Plant Lamp

    • Joe says:

      Hi Mary,
      I’ve tested something similar to this model before and it measured at about 5 mW/cm2 – and that’s at close range. So it is not suitable for light therapy.
      The wide positioning of the LEDs, wide beam angle and so on that you find in these type of ‘grow light’ devices in general make them inappropriate for light therapy.

        • Joe says:

          You need at least about 20mW/cm2 of light intensity for the minimum effects in the skin.
          For deeper than the skin you should be aiming for at least 100mW/cm2.

  28. dale says:

    I am very confused , about which red lite handheld laser is best for me to use I have a tendlite now I don’t know if 600 or 1100 is best for me to use on my back and shoulders and which laser is rated best for deeper penetration. which one is adjustable to cover a wider area or to pin point and area ?

  29. Haig Tutundjian says:

    Hey Joe:

    I’ve got your Red-IR Combo Mini unit; & I’d like to try it on an abdominal hernia which I noticed coming on about a month and a half ago.
    Since this unit’s only 6 of 12 diodes are IR (for muscular penetration) I’m cutting the Power Density in half from 200-100mW/ (@ 5cm.) to come up with 13 min. & 20secs.
    13:20 = 80 / (100 x 0.001)

    Also, I’m aiming the IR diodes to cover the affected area.
    Is my assumption correct?

    I thank you in advance for your help.


    • Joe says:

      Hi Haig,
      The beams of light from the 12 LED lenses do start to converge around 5cm, but not fully. So I don’t think you should cut the power density in half at that distance if you are aiming the IR LEDS on one spot. Maybe trim off 20% of the power density if you are going to calculate it like that. Red light may still be useful though, even if it has less penetration potential. Studies show systemic changes in hormones and reductions in inflammatory markers and such from exposure anywhere on the body.

  30. Gary says:

    Hi Joe,

    Can you recommend a starter light for someone who would like to use it for a bit of everything?!

    I would like to use it for knee crepitus, no pain just creaky knees. I would also like to use it for wound healing and general skin health and muscle recovery after exercise (or preventative as it seems to state on your website), maybe even hair growth.
    A big ask for just one device, I know. But if you could point out one product that work on all of these, using various distances, I would really appreciate it.

    Thanks in advance for your help.


    • Joe says:

      I do not make specific recommendations for medical conditions. For general light therapy as a proactive health / anti-stress tool, this might be useful:

      A broad range of wavelengths, useful for skin and deeper tissue. More importantly, it is quite powerful, which aids the penetration for things like muscles.
      You would use it close to the skin to target the deeper tissue, and use it from further away to cover a wider area of skin with appropriate light intensity.

      • Di says:

        Do you have any information re using light therapies for kidne problems.?
        Have bought redlight mini combo for other reasons.

        • Joe says:

          I have seen mostly animal studies on the kidneys, for things like preventing fibrosis and reducing oxidative stress, so it seems useful.
          I don’t recall anyone ever mentioning that they used the Combo Mini specifically for that.

  31. Lyle says:

    I have a p300 660nm light. Is that the optimum wave length for deep tissue penetration.? I want to use the light for wound/injury healing. I have read that 880nm is better and I can get a light that is a mix of the two wavelengths. Also , how close should hold the light to my skin and how far does the light penetrate?

    Thank You

    • Joe says:

      Hi Lyle,
      No, it is not the ideal wavelength for penetration. 880nm is also not ideal, for that or for wound healing. How close you use the light depends on what the power density of that light is at different distances. How far the light penetrates in sufficient intensity depends on the wavelength(s) and the power density, and also various other more minor factors.

      • Chris says:

        good question! I’m also looking for something to treat the inner ear (acoustic trauma). So you would definitely choose the IR wavelenghts for the inner ear? I read somewhere that the “more red” wavelengths have more healing potential, is that true?
        Do you think the 830 Mini also has enough power to make it to the inner ear?

        Can the “big” 830 Device be operated safely in a close distance to the ear? Is it loud when turned on?
        Thank you!

        • Joe says:

          Yes, definitely the near infrared range around 800nm for deeper tissue. Even if ‘more red’ wavelengths were better for healing (which they aren’t), they simply don’t penetrate as deep as the near infrared.
          830 Mini still goes up to and over 200mW/cm2 irradiance, so plenty of power output and penetration.
          The big 830 device is not loud. Just a quiet fan. I do not make medical recommendations as to how to use it.

  32. Dave says:

    Have you seen any research on existing keloid scar reduction or elimination with red light therapy? I found one reference but it talked about red light therapy immediately following a dematological operation and got good results, but wasn’t sure about an existing scar that’s been around for years. Thanks!

  33. Shari Douglass says:

    I have a lamp that is 12W Deep Red 660nm LED, that I am wanting use for facial and anti-aging purposes. It produces The lamp produces approximately 250W/M2 @1 foot. [25mW/cm2 @1 foot]. Although you have been very detailed in your description and equations, I still think I am not calculating my time incorrectly. I was wondering if you would be so kind to give me the optimal time of exposure and how often I should use the lamp. I was under the impression that 4-6 Jules was optimal per exposure, but I don’t know if you have come to the same consensus. Thank you for your help!

  34. Kate says:

    I have just ordered a couple of mini lamps. I was wondering if you could recommend a material to block the light rays so I can specifically target a healing wound. I also have rosacea and wish to shield non-affected skin whilst targetting my problem areas.

    • Joe says:

      I can’t remember that device specifically. As long as a device has a wavelength output in the 600-900nm range, it will have some good effect. It should also have between 20 and 100 mW/cm2 power density output hitting your skin for wrinkles.

    • jdblack6 says:

      I don’t know if this will help Danielle at all, but I have the red LightStim (which includes near IR) and although I have seen some skin improvement, I don’t know how much, or if any, of that can be attributed to LS. I went with red because I also wanted to use it on bruises and sore muscles, and it seems to do very little to nothing for even small bruises with a 30 minute treatment time. Anyone considering the LS devices should take the time to look at all the options before springing for one. I went with LS because they’ve been around for years and are a well-known company in the US, but I’m here because I’m now convinced that the LS simply is not powerful enough to deliver results. (They make a point of not disclosing the power output on their devices, but the lackluster results on bruises from the device they specifically sell for healing doesn’t instill confidence)

      Really appreciate this website and all the info here. Thanks for making this info and the devices available, Joe.

  35. kris says:

    I have scar tissue between first and second metatarsals from a lisfranc injury in a fall three months ago. They didn’t catch it in the initial x rays. I am opting to wait and watch instead of surgery, and wondering if red light would be a possibility for eliminating the scar tissue? If so, which device and how long?

    • Joe says:

      I don’t think light therapy will ‘eliminate the scar tissue’, but it may help help to some extent in the long term at improving. Some research indicates that light therapy is perhaps useful as a means to prevent scar tissue at the time of injury, rather than actually eliminate well established scars years after the injury.

  36. kim says:

    Advice for choosing a light for two very different purposes?? I’d like light therapy for facial skin wrinkles, and also a light for deep muscle healing. I am concerned that your combo light will penetrate too deeply for facial skin, and not have enough LEDs to truly help deep muscle pain. Is this correct? Would I need two different lights?

    • Joe says:

      The amount of LEDs is irrelevant because there are different classes/power of LEDs.
      The factor that matters is the power density / irradiance (mW/cm2). You need higher than 100mW/cm2 for deeper penetration in general. You want less than 100, but more than 20mW/cm2 for skin treatment.
      So what that means is you need to adjust the distance you use a device depending on if you want deeper penetration or not.
      So you would use it closer for deeper penetration. Further away for skin treatment.

  37. Jenn says:

    What are your thoughts on the Abrastim 200 device? For a $35,000 device I would like to understand if it is superior in any way given it’s high price tag

    • Joe says:

      I have never heard of it before, but it doesn’t look like a light therapy device. From what I can see, it seems to be a facial massage device, with an optional LED attachment of 0.005 watts power.
      I don’t like to criticise other vendor’s products without knowing the full treatment, however I will say that in general, any device with such a low power will have absolutely no effects in terms of photobiomodulation.

  38. Francie says:

    Hi – my daughter had surgery on her nose and upper lip. We were thinking that either the red and/or infrared light therapy might help stimulate healing. Can one of your lights be used for that purpose, and if so which one? And also what dosage (time per treatment etc, how far away from the skin etc) should be used.

    • Joe says:

      There are studies indicating that red lights will potentially be useful for superficial skin damage from surgery. Near infrared (better penetration) will presumably be better for more substantial deeper tissue damage from surgery. In your case, maybe a combination of red and near infrared light would be the most ideal. Using the light at around 50-100mW/cm2 is probably ideal for fairly deeper surgical damage. 5-10 minutes is fine from about 10-20cm away.

  39. Pooja says:

    I read the reference you provided for dosage details for back pain and muscle pain. It says the total energy irradiated on muscle should be 83.4 J. But the dosage column here says 80 J/cm2 is right. So what should I consider – The total energy irradiated(J) per muscle or energy density(J/cm2) per muscle?
    Could you please explain?
    Thank you!

    • Joe says:

      The correct dose units are power density – J/cm2. Total energy is not useful.
      Those referenced studies are just to get an idea. For muscles I think you need quite a large dose (70J/cm2+), from a light source of 100mW/cm2 or higher.

  40. Lisa Query says:

    Joe, can you please direct me to a specific brand/brands at reasonable cost of a solar meter to check power denisity on various led/red light therapy devices? Amazon seems to have several products entitled “solar meter” for over 200 bucks. That seems overkill for checking a couple of lights. Help? Thanks!

    • Joe says:

      Due to the materials involved in this kind of sensor, that’s the normal price, unless you can find one second hand on ebay or somewhere. Perhaps you can buy one that can be returned for a refund.

  41. Kat says:

    Hey Joe!
    Does NIR not work for wrinkles and collagen production? I hear it kind of just bypasses the surface/superficial layers of skin and mostly benefits the deeper tissues, muscles, organs and bones. BUT, your infrared light says it does say the spectrum includes SOME visible red (680 nm), so what percentage would you say is 680 nm and is it enough for me to see some surface skin results (light wrinkles and collagen boost)?


      • Joe says:

        There are studies showing that near infrared light benefits skin to a similar degree as red light does. I remember seeing studies about near infrared helping hair growth even more so than red did. I have seen it studied to help wound healing, eczema, etc – various skin issues.
        So yes, it is studied to help normalise collagen production and prevent wrinkles.
        Near infrared does penetrate deeper than red, which is why it is favoured for deeper tissue like muscles and joints.
        I think the reason that red is favoured for the skin, when both red and nir can work, is that red has slightly better physical properties there because it doesn’t evaporate water to the same extent. So red light is better for skin hydration.

  42. Keith Reynolds says:

    I have aBulb: ABI 25W Deep Red 660nm LED Light Bulb. I have through these posts here and am confused a bit. I would like to know the time and distance to use this for tissue repair, arthritis, genital assistance, and hair regrowth. How long should I use the light and from what distance? I would appreciate the answer in US terms. Thank you.

    • Joe says:

      To use a light for therapy, you need to measure the power density as described in this article. Without the power density readings, there is no way to advise on how close or how far to use your light.
      In addition to measuring the light intensity, you should also measure the EMFs.

  43. Jody Rein says:

    I have severe arthritis in my knees with no cartilage between patella and femoral groove. Planning on partial patella femoral knee replacement in a few weeks. I would also like a product that will work on my facial wrinkles and my husband’s hair loss. What product would you recommend and how to use it? Will the near ir rays heat up a metal prosthetic device? Will it help healing with the prosthetic device?

  44. Gloria Butner says:

    Pretty technical. So if I want to improve my facial collagen how strong of a bulb do I need?

    • Joe says:

      Some studies I have seen say a light intensity somewhere around 20-50mW/cm2 would work well for the skin of the face. 5 minutes at that intensity would be enough.

  45. Jay says:

    What is your recommendation on type of light (wavelength, frequency) and dosage for neuropathic facial pain (trigeminal nerve)? Thank you!

  46. Beth Cole says:

    In the nih acne studies a combination of blue and red ight therapy proved to be the best combination. Did they use a light with both red and blue lights or 2 separate lights? If two separate lights were they used in the same session or alternating sessions? If two separate lights in same session which color is used first?

    • Joe says:

      Blue light kills acne bacteria via a light-pigment reaction. It also harms the bacteria through direct damage to DNA. This same DNA damage from blue light also happens to our cells – over time harming our eyes, ageing our skin, etc.
      So while a combination of blue and red light might give the best short term results in 1-2 weeks acne studies, I strongly suggest not using any source of blue light in practice. Stick to the red-only lights, which are still almost as effective as red-blue in the short term, yet have much better long term safety and beauty effects.

  47. janis says:

    I wonder if I need to wear eye covering when I put the infrared mini on my face for sinuses for about 15 minutes a day.

    • Joe says:

      There is no reason to think it (near infrared wavelengths in the 700-850nm range) harms eyes in any way. The studies point to benefits if anything.

  48. kcspringer says:

    Purchased a Red Mini 670 to use on eyes for macular degeneration. Many sources support red light use for this. While I understand the dosing discussion in this article, I can’t find specifics anywhere regarding whether eyes should be open or closed, or for that matter any other concrete suggestions for therapy on the eyes. If there’s anyone using red light for eye treatment who’d like to share their routine, I’d be grateful to hear it.

    • Joe says:

      Eyelids closed would help to scatter the light throughout the eye more evenly. From looking at the studies it seems that 670nm is the favoured wavelength and a mid level intensity of light such as 50mW/cm2 works well. Short sessions such as 2-4 minutes seems to be studied.

  49. Llama says:

    So if I’m doing my math correctly…if I wanted to use the light to penetrate into the brain. Placing the light directly on my forehead. I would only need to use it for 5 seconds to be at 6j/cm squared? That doesnt seem long enough….

    • Joe says:

      Hi, I am not sure which light (quote: ‘the light’) you are talking about. If you want to achieve a dose of 6J/cm2 in 5 seconds, you would need a light intensity of 1200mW/cm2.
      This intensity is higher than you see in the typical photobiomodulation study, so you might consider a lower light intensity and a longer treatment time.

    • Xan says:

      There are infrared light hats for brain treatment. You can also find specific instructions for making your own if you do a search on Cossack Red Light Therapy Hat.

  50. mrslightbrown says:

    Your website is absolutely fantastic!!
    I just bought the Combo body light. Waiting with baited breath. In the meantime I’ve dragged out an infrared lamp from the attic. It purports to emitting from between 2-25um, so 2000-25000nm. Doesn’t mention energy flux. I’m wondering if using the lamp until my combo light arrives will be beneficial? Do I need to use it at a distance that doesn’t cause too much heating of the skin? I’ve read one study of a face mask emitting far infrared light at 900-1000um, 35mW/cm² resulting in increased collagen and elastin. I haven’t found anything on the affect of a 2-25um device. Any thoughts?

  51. Patricia says:

    HI Joe and THANK!! My dude…I just bought infrared light device 760nm & 830. I want use it for artritis and eyes…do you think the Red-Infrared Combo Light 620 670 760 830 will be better for me…is safe for eyes?
    Thank you!!Patty

  52. Edson says:

    Hallo, thank You for the amount of useful informations on red and NIR lights. I have a question: In case I want to buy a device to use for skin and deep use (wrinkles and thyroid issues) I can orient myself on a 850nm only and adjust the time and distance according with the purpose or it’s better to have a Combo and use different wave lenght for skin and for deep tissues? (like 650/850).. Thank you Edson

  53. barbs says:

    Just purchased red light 670nm device *in the square red box and would love general info on duration, distance from device for anti aging benefit to face/neck. Not enough won’t do a thing and TOO much wont do a thing.
    Is hanging the light preferred to having on a vanity with light facing area?
    I have read anywhere from 5 – 20 mins *or does it even matter? At 10 – 30 cm away. Which? Is a particular distance better to receive results or who really knows and make a guess If desires are not met after the 6 – 12 weeks of use once every other day – or maybe use twice on one day – who knows? does one start over the process?
    I can mess up a recipe to make ice cubes. Some general use info would be soooo appreciate from somewhere.

  54. Anonymous says:

    This is very helpful; thank you. If you are exposed to non-optimal lighting with more blue light in it (in my case 10,000 lumens of LED lights that emit somewhat less red light than sunlight does), would that tend to increase the ideal dosage for red light?

  55. Charles says:

    Does red light therapy result in temporary improvement of fine lines and wrinkles, or permanent? By “permanent” what I mean is if someone gets a face lift that sets the clock back so they look 10 years younger, then, while they will age normally from that point on, they will always look 10 years younger than they otherwise would have. Temporary improvement is what Botox gives. Six months after you’ve stopped using Botox it is as though you never did.

    • Joe says:

      It is better than both botox and a face lift. Light therapy improves your cells’ own natural energy production.

  56. Gabrielle says:

    I want to buy the Combo but don’t know if you ship to Chile and if you send with DHL (or any other ).

  57. Nicole says:

    Hi Joe, I have a red light Mini 670. If I keep it 25 cm from my face for 15 mins, would that be enough for skin therapy (just youthfullness, no specific problems other that wanting a firmer skin and prevention and improving small spots of hyperpigmentation? Thanks!

  58. Christina says:

    The calculation: Time = Dose ÷ (Power density x 0.001)
    is incorrect math wise. If you use your example of 1J/cm2 ÷(5mW/cm2 x 0.001) above it actually calculates to 0.0002 seconds. Please explain as I think I am missing something

    • Laura says:

      No, it is correct. It calculates to 200 seconds.

      When calculating any maths equation, you have to follow the ‘BODMAS’ rule of order. This is the order that you complete the equation. brackets > division > multiplication > addition > subtraction. You are going wrong because you are just calculating from left to right, ignoring the brackets, which is wrong.

      So you calculate the brackets (5mw/cm2 x 0.001) first. This gives 0.005, so the new formula is 1J/cm2 ÷ 0.005. This gives 200 seconds.

  59. Mariano says:

    Hello is there any chat por 3w 12p degrees LEDs and/or a way to measure ir without the solar device? Shouldn’t multiple leds emit higher power density than 1 led? Thanks in advance

    • Joe says:

      You have to measure the output because different LEDs have different energy efficiencies, different lenses have different light transmission rates, different LED drivers have different energy efficiencies, etc.
      Technically the multiple vs single LED is irrelevant because you can have very powerful single LEDs, or very weak multiple LEDs. Assuming all LEDs being tested are equal…..When the beams of light from multiple LEDs converge, the power density will obviously be higher than if there were only one LED, yes.

  60. Frank says:

    The instructions that came with my Combo Bodylight received today state :-
    power density : 200mW/cm* (at 7.5cm).
    The table above in this great article : 200mW/cm* (at 15cm).
    Also a difference in 100mW/ cm* figures.
    Can you please say which is correct.

    • Laura says:

      Both are correct.
      The table above is referring to the Combo Light Device (not the Combo Bodylight).

  61. Tali says:

    I’m thinking about purchasing the Red light device for treating rosacea. what is the suggested treatment time and distance?

    • Laura says:

      We can’t give advice for specific conditions. All I can say is that in the studies on sensitive skin, a lower light intensity and shorter treatment time works best

  62. Anonymous says:

    Hey Joe,

    Did you ever post power density/distance charts for the Mini Devices? I am looking for this as well (Anthony and Todd also asked in 2016). The product pages only show the distances that give 20 mW/cm² and 200 mW/cm², and I don’t have a light meter.

    Can any of the Combo lights be switched for red or IR only?

    Thank you.

    • Laura says:

      You get all of that in the product instructions so you don’t need a light meter.
      The combo lights don’t offer that. If you want separate red or infrared only then it is best to buy the separate red or separate infrared light devices.

  63. jim howells says:

    If you want to treat a deep tissue area with 40J, and also want to treat a skin issue directly over the deep tissue area with 6 to 10J, would you treat with the 40J for several weeks and then do the 6 to 10J., I haven’t been able to find any thoughts on treating deep and skin issues in the same area.

    If you want to treat a deep tissue problem with 40

  64. Outside_Observer says:

    So would the dosage for muscles (or any other internal area) be compatible with the dosage for skin health?

    For example, if I gave myself a large “muscle” dose of light, would that be so strong that it would cancel out the effects for my skin?

  65. Vicki Carnes says:

    I have several strikes against me as, #1, I am an American and have trouble converting centimeters to inches and, #2 I have a serious mental flaw about mathematics so I need just a wee bit of help with some general parameters that I think I am trying to figure out. I purchased the Combo light thinking that I could use it on my face for skin rejuvenation and also use it for muscle rehab in my tailbone area. Now I am wondering if the light I bought is appropriate. For my face, I think I should use it at about 12 inches for 5 minutes 3-5 times a week? for deeper treatment of my coccyx pain, maybe 3-5 minutes at 6 inches daily? Also, should red light therapy be considered a long term program? or should breaks be taken at certain intervals like weeks or months?? Can you tell me if I am in the ballpark?

  66. Lena Alsayegh says:

    Hi, I’m really confused about these calculations. I was considering purchasing a facial device that is 640nm, 32W, and positions roughly 10cm off the face, but I don’t think I have enough info for these calculations. Can you guess if it’s still effective, and how long a treatment would be? After reading your info, I found another device, a bulb, that’s 670nm and 12W, but I wouldn’t know how far to place it and how long to use. I’d buy one of your bulbs but they’re a bit pricey for me right now and the 670nm’s sold out. Any info appreciated, including when you’ll restock. Thanks!

    • Joe says:

      Hi Lena,
      The information you have given is not appropriate to determine anything relevant for light therapy. The Watt rating means nothing without details on the type of lens and efficiency of the LED driver etc.
      Everything is back in stock.

  67. Tony says:

    Can you tell me if you know anything about the face masks out there. Regarding there usefulness dosage etc. The ones being sold do t tell you much part from there red light range of 660 to 800 etc.

  68. Tony says:

    Hi Joe,
    Very interesting article thank you for taking the time to write it. I’m still confused regarding the time and distance to use my half body device. The booklet shows the following power.
    > 200 wm/cm2 @ 0 inch
    >100 wm/cm2 @ 3 inch coverage 25x 14″
    > 82 wm)/m2 @ 6inch coverage 31x 18″
    > 53 wm/cm2 @ 12 inch coverage 38 X 24″
    > 30 wm/cm2 @ 18 inch coverage 44 X 32″
    The instructions say between 10 to 20 mins that’s going to depend on distance and what you want to achieve.
    The device has a NIR of 830nm and deep red at 660nm.
    I am using it for skin for wrinkles and collagen reproduction in the face. Osteoarthritis on my left knee and top glad of body for boosting mitochondria.
    I’m using it for about 15 mins on the face at about 10inches is this too much.? Face feels alot dryer after wash than normal. Not sure if related.
    Your thoughts would be much appreciated.
    Kind regards

  69. Anna says:

    Hi, I bought the Red Light mini #670, i want to use it for my face for wrinkles, skin tightening and a little skin pigmentation. I have used it 3 times so far at 12 inches away for 15 minutes every other day.
    Can you help me and tell me how far away from my skin should it be and how long of a session to get the best results also how many days a week? Thank you, Anna

  70. sveiki says:

    Wow… I found those instructions a bit hard to follow. Are there reputable companies selling these devices along with reliable, simple instructions, e.g., 2 inches from skin for 15 minutes, 5 inches from skin for x minutes, etc.?


    • Joe says:

      These are not specific product instructions. This page/article is a light therapy dosing guide.
      Our products come with reliable, simple instructions, yes.

  71. Bob in Dallas says:

    Hello Joe. Thank you for the informative “Guide To Light Therapy Dosing”.
    I am stuck on understanding your first graphic regarding Power Density. The graphic displays power densities as measured with a light power meter. But, when I try to calculate the same measurements using the formula (mW/cm^2), I get totally different numbers. For example, calculating the Power Density of a 1200mW Infrared Light Device at a distance of 5cm, I get a Power Density of 48mW [i.e., (1200mW / 5cm^2) … or … (1200 / 25 = 48) ]. But, your graphic displays a power density of 500mW @ 5cm for a 1200mW IR Light. It seems like my calculation is off by a decimal point, but I don’t understand why. What am I missing?

    • Joe says:

      Hi Bob,
      You refer to mW/cm2 as a formula, but it is the units or a measure of light intensity, not a formula for calculation.
      It is not possible to calculate power density like that, nor is the Infrared Light Device a 1200mW device.

  72. Thomas A Walters says:

    I am a bit confused on the formulas. I want to use this for retina therapy and want the correct formula. I bought a solar meter and directly measured my output in w/m2 (at a specific distance), I converted to mw/cm2 by multiply by .01 (actually used online converter). so now to plug it into the formula. the problem i have is that you have 2 versions of the formula on the same webpage:
    Power Density x Time = Dose

    Fortunately, most recent studies use standardized units to describe their protocol:

    Power Density in mW/cm² (milliwatts per centimeter squared)
    Time in s (seconds)
    Dose in J/cm² (Joules per centimeter squared)

    Then in the next couple paragraphs:
    Now you should know your light’s power density (varying by distance) and the dose you want. Use the formula below to calculate how many seconds you need to apply your light for:

    Time = Dose ÷ (Power density x 0.001)

    Time in seconds, dose in J/cm² and power density in mW/cm² – which is the same units now with a .001 multiplier

  73. David says:

    Just checking in with you since I’m not good at math. Following your application times recommendations for General Skin, am I correct that your Red 670 Light Device at 10cm distance applied for 3 minutes would deliver 18 Joules cm squared?

  74. David says:

    so my most recent question was wrong proving how bad I am at numbers. In reviewing my calculations using your numbers for skin using your 670 light device (which I own and use), at 10 CM, Power Density is 180 x time ( 3 minutes ) equals 180 seconds x 0.001 which equals 32.4 Joules per a treatment session. Am I correct? Thanks.

  75. Luis says:

    Hello, can you please tell me if I can use a flooding led light lamp 60W multi color. For health reasons such as brain, eyes, skin… etc?.

  76. Anonymous says:

    Do your products work for fat and cellulite reduction? If so, what is the best dosing to reach the fat layers – abdominal or thigh.

  77. Jay says:

    Hi, I have bought both the red light mini and combo red/infrared light from you about 1 year ago. I am wanting to start using them again to help with facial ageing and collagen production but I have lost the paper with the instructions. Could you please advise on length of treatment and distance to hold the lights. Thanks, Jay.

  78. Anonymous says:


    If I would use my IR combo light at 450mW/cm2 vor 15min (900) Seconds would it be at 405J/cm2

    Is that to much?

    • Joe says:

      Correct, yes. That is considered a high dose and might cause skin warming. It will provide effects in deeper tissue and possibly systemic, as the dose received by deeper cells and the passing blood will be more ideal.

  79. Janis Bryant says:

    I purchased a 670 model and I’m very happy with it. Now I have 5 broken bones in my left foot and it is wrapped in a heavy plastic guard with layers of felt material and everything is secured by an ace-like like bandage about 6 inches wide and very thick. How many infrared light penetrate through all that fabric and plastic ?

  80. Louise says:

    This is wonderfully informative, thank you. I contacted the seller of the LED device I purchased who told me that the powder density is Red (630nm): 3.1mW/cm2+20% and Near Infrared (830nm): 1.0mW/cm2+20%. I’m confused how to apply the +20% to the equation. Can you please help? Do you know what the +20% means? Thank you.

    • Joe says:

      Hi Louise,
      I suppose it just means plus 20% intensity. The exact figure for each device from that seller could vary by 20%. So the real light intensity might be up to 20% higher.
      Those are really low power density readings. I would consider 20mW/cm2 as the real minimum you need for light therapy. I suppose you could go as low as 10mW/cm2 if you don’t mind really long session times and only getting effects in the outer most layer of skin.
      3.1 + 1 = 4.1 mW/cm2 and even with +20% on top of that, it’s still far too low for any effect.

  81. Biju says:

    Hi Joe

    Thanks for all the info on your site.

    Just wanted to check, do the IR-only devices also provide skin-related benefits, along with deep muscle and joint benefits?

    OR, do they make nil or negligible effects on the skin?


    • Joe says:

      When you look at studies for things like wound healing, acne, and other skin issues (where they are comparing red vs infrared), the infrared lights still give benefits, albeit less benefits than the red.
      This is a good example:
      “treated with red and infrared LED showed clinical improvement…. Red LED was much more effective than infrared LED”

      So red light is better for the skin, but infrared light is still giving skin benefits.

  82. Dave 2 says:

    Hi Joe,

    I recently bought your Combo light, and it looks and feels like a solid, well-built device of high quality.
    I hope you can help me with these two questions:

    1. With this Combo Device (, at roughly what distance do the lights start to converge (as you mentioned for the smaller version in a previous reply)?

    2. Before the conversion point, is the irradiance for each of the four frequencies roughly 25% of the figures listed in your chart? So for example, your chart specifies 200mW/cm2 in total at 15cm. Assuming that this is before the conversation point, is the irradiance for each of the four frequencies (620 nm, 670nm, 760nm and 830nm) roughly 50mW/cm2?

    • Joe says:

      Due to the COB LED and single large lens, the lights are already converged/mixed before they even leave the lens.
      It doesn’t make sense to think of splitting out irradiance by wavelength in a device such as this. All of these light therapy wavelengths work on a very similar mechanism in our cells, so the overall light beam is just one combined light therapy source.
      Think of it like coffee – if you mix 4 different types of coffee into one brew, the taste and flavor of the resulting drink is still a normal cup of coffee.

  83. Thomas says:

    Can a mini bulb be used in a lamp that is rated 25W max? Most lamps out there don’t have LED rating sticker on them. Thanks

    • Joe says:

      Yes it can. That ‘xx watts max’ generally just refers to how much heat a fixture can support. With LEDs it is not relevant

  84. Tano says:


    What would you recommend for Hyperacusis/Tinnitus/Ear and trigeminal nerve pain?
    I was looking on the Infrared Light Device Mini and Infrared 830, I don’t know which would be better.
    I read all the technical specs, but I really don’t understand when someoune should I choose the Mini and when the 830.

    Thank you

  85. Thomas says:

    This is a great resource for calculating strength and time for healing the skin, but does someone know how you modify the formula for healing of deeper tissue? I have large veins I hope to heal. I estimate that their top is under 1mm of skin, and that they go about 3mm deep.

    I also wonder whether someone has a formula for calculating time and distance to the scalp for a good dosage to the brain?

    Thanks for any help!

    • Joe says:

      The same formula applies for deeper tissue – you just need higher overall doses. All of the light therapy is ultimately being applied to the skin. Only a percentage of it will penetrate down, and less and less will get deeper into the core of the body.
      So the deeper the tissue, the higher the dose you need. 1 or 3mm would still be considered surface tissue and so you won’t need a high dose.

  86. Anonymous says:

    Hi I have bought your device with NIR at 850nm for a specific issue. However, in the study where I can get the required dose information from, was done with NIR at 800nm. Do I need to do anything special or just use your simple calculation in this article?

    • Joe says:

      You just calculate the dose yes, even if the wavelength you found in the study is slightly different.

  87. Greg says:

    Hello i want to buy and use infrared light for the brain. My mother has dementia.
    As i understand i should take the 830nm led.
    If that is correct how much time should i use it and at what distance from skull?

    Thank you

    • Joe says:

      Hi Greg, yes the 830nm wavelength or close is appropriate. It offers good penetration and is backed by a lot of research.
      I prefer skin contact when targeting deeper tissues like the brain to maximize the penetration. However our lights can be used from any distance up to 5 inches for the brain. Usually you would press the light into the forehead because hair blocks light. If the hair is very thin or bald, then it can be used anywhere on the head. 3-8 minutes.

      • Simon says:

        Hi Joe,
        I would like to inject light into the head to reach neurons.
        As I understand, I need to select:
        1) near infrared light, so around 800nm should be good?
        2) Power density should be something like 500mW/cm2 for 0.2 to 12 sec to reach 0.1 to 6J/cm2? This seems very short time stimulation. Plus, I can only do that 2 to 14 times per week? Or maybe I’m wrong here and I need to consider the distance between the LEDS and the neurons?
        3) I read in article that we only get 5% of the fluence of light in the brain. That meen that we have 25mW/cm2 if have 500mW/cm2 outside? Or maybe we have 5% of what is remaining after the power dissipation through skin, bone, water, etc?
        4) Let’s say that the 25mW is correct. That meen that I need to multiply my stimulation time by 20 in the question 2) to have the correct amount of energy / cm2? So it will be 4 to 240 sec? That seems short again 🙂

        Thank you for all, that is a great document that you have here!

  88. Raphael says:

    Good day,
    in the studies often only one wavelength is given. If it says at 630 nm 5 joules, maybe you should operate the device only with the spectrum? Or should one rather also include the 830 nm directly in calculation?

  89. Heather says:

    What device can I purchase to measure the red LED masks to determine if they are accurate or a “hoax” device?

  90. John says:

    Hi Joe,
    I would like to inject light into the head to reach neurons.
    As I understand, I need to select:
    1) near infrared light, so around 800nm should be good?
    2) Power density should be something like 500mW/cm2 for 0.2 to 12 sec to reach 0.1 to 6J/cm2? This seems very short time stimulation. Plus, I can only do that 2 to 14 times per week? Or maybe I’m wrong here and I need to consider the distance between the LEDS and the neurons?
    3) I read in article that we only get 5% of the fluence of light in the brain. That meen that we have 25mW/cm2 if have 500mW/cm2 outside? Or maybe we have 5% of what is remaining after the power dissipation through skin, bone, water, etc?
    4) Let’s say that the 25mW is correct. That meen that I need to multiply my stimulation time by 20 in the question 2) to have the correct amount of energy / cm2? So it will be 4 to 240 sec? That seems short again 🙂

    Thank you for all, that is a great document that you have here!

    • Joe says:

      Any wavelength from 740nm to 850nm has a good penetration.
      500mW/cm2 will give good effects in deeper tissue but you should do it for much longer than 12 seconds, at least several minutes.
      It is true that only a percentage of the light hitting the skin will penetration down into the brain. Most is absorbed in the skin/bones etc.
      5-10 minutes will be reasonable with one of our infrared lights.

  91. Maria says:

    This article was so welcome – there are so many devices out there, and I wonder about all of them…. hahah. I bought the FOREO UFO (the little masking puck) mainly for the warming and no-mess masking, which it’s lovely for, but then went down the rabbit hole of anti-aging and wondered about the LED therapy it supposedly offers -but I doubt it truly does anything with that bit of light and the tiny amount of time it’s meant to be going all over your face (90 seconds total, so a fraction of that at any point on your face!). I’d love to ‘test’ it per your article – is there a specific non-costly solar power meter you recommend, or is it your experience that solar power meters are generally good? Also, do you happen to have tested these UFO devices by any chance? It’s funny, I asked the company and they literally refused to answer me! (which now makes me determined to figure it out…)

  92. Adrienne Greenfield says:

    A health care provider related that a simple shop hallogen 500watt lamp is fantastic. Any feedback would be appreciated.

    • Joe says:

      Fantastic for light therapy? They are not correct. Not only is it not studied or proven for this purpose, but the heat output makes them unsuited for skin treatment or deeper tissue treatment. Light therapy should be done with a ‘cold’ source of light because tissue heating will inhibit the target mitochondrial enzymes.

  93. James says:


    I appreciate your post and information My device claims 7J/cm2 power output and 27J/flash it’s directly above the skin. I’m using it once per week and doing maybe 10 flashes in each area the flashes are a second or less , what frequency protocol should I use and is this current amount too much

    Alternatively would something like 2 flashes 3x per week be better? Thanks

  94. Annabel says:

    Please could you tell me what the power density is for the Infrared Light Mini at 0 cm, i.e. when it touches the skin? The leaflet that came with the device only shows the power density from 10 cm (200 mW.cm2) to 90 cm (10 mW/cm2). Thank you.

  95. Julia says:

    Hello, I have a small device, it is very light and charges via USB. Its power is only 15W and it has 42 LED bulbs. The manufacturer claims that device power density is 100 mw/cm2 at a distance of 30 cm due to the fact that it has reflective mirrors. Do you think this is possible? And do reflective mirrors affect the efficiency of the device? I will be very grateful to you for your answer!

  96. Simon says:

    Hi Joe. Any recommendations on using red laser light (LLLT), Infra-red or red LED for kidney treatment? It is getting confusing, depending on what you Google but I am assuming – that conundrum aside – the power would need to be near 1000 – 1100 Nm? Thanks.

    • Joe says:

      A near infrared LED light device with wavelength around 750-850nm is my suggestion. The irradiance / power density should reach an excess of 200mW/cm2 to get effects in deeper tissue such as kidneys.

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