Universal Dosage Calculator for Red Light Therapy! Find your optimal time per session!
The science of Red Light Therapy still has a lot of grey areas in terms of how to properly dose the light! It is even more confusing by companies using inaccurate solar power meters, promoting high irradiances, and not always reporting the same units of intensity. And even the clinical studies report a wide range of dosages and intensities.
Lets say you have a light panel with 3rd party testing like GembaRed, and you read a study that says a dose of about 6 J/cm^2 is ideal. So how do you calculate the distance and time it takes to get this dose? Well, we originally made a table in our FAQ to help find the correct times, but probably most people are not using it.
Or you can do the math here, but sometimes it seems daunting:
Time (seconds) = [Dose (J/cm^2) x 1000 (mW/W)] / Irradiance (mW/cm^2)
Now, you can just "plug-in" the dose and irradiance for your light into our handy calculator, and it will tell you how long to use it for! The best part is that it works for ANY light-therapy light, as long as you have the accurate 3rd party irradiance measurements.
The "default" numbers above are actually for a GembaRed Rex at 0 inches with irradiance of 7mW/cm^2, and a desired dose of 6 J/cm^2. We see the time it takes to achieve that dose is 14.3 minutes.
I found that my ideal daily dose is between 4 J/cm^2 to 10 J/cm^2 for general wellness. If you are spacing your doses out every other day, or just a few times a week, then you could increase the dose higher as needed.
Update 1/13/2022! Joules Per Centimeter Squared Per Minute?
In the never-ending efforts for companies to cover-up their false intensity claims, they may tell you to ignore intensity entirely and base your dosing calculations on the "J/cm^2 per minute."
The J/cm^2 per minute is a metric sometimes called "fluence" in the studies because it describes both energy and time together.
This is actually a nice convenience, because if you know you want a 10 J/cm^2 dose and a company tells you their fluence is 2.5 J/cm^2 per minute, then the math is a simple division and you know you need only 4 minutes to achieve that dose (minus reflection losses if you are standing 6 inches away).
But we know that the "J/cm^2 per minute" actually is easily converted to intensity of mW/cm^2 through the magic of simple math.
1 Joule/Second = 1 Watt
1000 mW = 1 W
1 minute = 60 seconds
So we know that when someone tells us the Joules/cm^2 per minute, that is a quick conversion equation.
mW/cm^2 = J/cm^2 per min * 1000 ÷ 60
For example:
2.5 * 1000 ÷ 60 = 41.66 mW/cm^2
Thats it! Easy conversion from J/cm^2 per min back to mW/cm^2, the industry standard measurement. To make it easier, we put it into another calculator!
Conclusions:
Remember that it is a common fallacy that "more power" means faster treatments. It has been shown that due to the biphasic dose response that the Law of Reciprocity does not always apply to light therapy. That a "faster dose" does not always mean the same effectiveness, although it might appear to save a busy person some time. Read more about intensity and effective doses on our earlier blog.
Ultimately there is still a lot left to learn about proper dosing with red light panels. But I feel we must be firmly grounded in the science and accurate measurements, otherwise we may never be able to replicate results or discuss photobiomodulation scientifically.
-Andrew