I write huge articles explaining red light therapy because it’s just not obvious how to get a proper dose. Incorrect dosage leads to treatment failure.
Irradiance is a huge problem in red light therapy shopping. One cannot trust the irradiance values manufacturers give because so many vendors use the wrong meter type to measure light delivery. Mito Red Light now gives us fluence, a solid way to measure a device’s power.
While it’s cumbersome to calculate treatment time using irradiance, it’s crazy how easy it is to calculate treatment time using fluence.
Get High Power, but Not Too High
Red light therapy is the low energy delivery of photons.
The biological magic stops if the light is delivered too quickly.
But a powerful light gives you a shorter treatment time.
Therefore, you want the light with the most power that reaches but does not cross over that upper threshold.
You Say Watts, I Say Irradiance
Comparing wattage matters when buying a refrigerator or other appliance, but it’s a bit of a useless value when comparing red light therapy devices.
Wattage is not a reliable value that informs you of how quickly the device delivers light.
A 300 watt device can deliver 200 milliwatts per sq. cm. of photons. Â It could also deliver 20 milliwatts of photons.
We can’t know just by looking at the wattage value. A red light therapy device is a black box. No wattage or amperage statement on the device tells us the photon irradiance.
What we need is the photon delivery value, which is irradiance.
Irradiance is the rate at which the light delivers photons from a given distance per second.
The device’s wattage doesn’t tell us the irradiance.
We need to get that from the vendor who measured light output with a proper meter.
Irradiance is No Longer Above Reproach
We usually use irradiance to calculate treatment time.
Manufacturers routine usely solar meters to measure LED light delivery, severely inflating the irradiance values printed with red light therapy devices.
Once one vendor inflated their irradiance values, others did too so as not to seem weak by comparison.
Inflated irradiance values lead to vastly understated treatment times, which lead to underdoses, which lead to failures.
By publishing fluence, Mito Red Light gives us a valid value to calculate treatment time.
Use irradiance when you have a valid value. Use fluence when you can get this value.
Below you’ll learn how to calculate treatment time using irradiance or fluence.
How to Calculate Dose Using Irradiance
If you have a reliable irradiance value, you can use this guide to calculate your treatment time per session.
I will show you how in this section.
However.
These instructions are here for the absolute red light therapy geek.
I encourage anyone who has a life to buy from a vendor that publishes certified fluence values, and then you can just skip this section.
You need a reliable irradiance value for any of this to make sense.
Are you sure you don’t want to skip this section?
You’re still here?
OK, let’s talk about how to calculate treatment time given a reliable irradiance value.
Irradiance is Per Second and Expressed in Milliwatts
Let’s say a red light therapy device delivers 50 milliwatts per square centimeter per second, which we write like this: 50 mW/cm^2.
That irradiance is incomplete. It delivers 50 milliwatts from what distance? In what amount of time?
The distance has to come from the vendor too.
An irradiance value is meaningless unless we know how far away the light is from the target.
For the sake of this example, we’ll pick 6 inches as the distance, and we are assuming one second at the interval. Now our irradiance is 50 mW/cm^2 at 6 inches per second.
For time, you should know that “irradiance” assumes a one second interval unless stated otherwise.
Everything you need to know about dosage is in that statement:
- 50 milliwatts is the energy
- per second is the time
- the given distance is 6 inches
We will use this data to calculate session time to get a target dose.
You can always skip this and read the easy fluence instructions.
Don’t say I didn’t offer you an out.
Treatment Time Calculation Step 1: Convert Irradiance to one Minute
Irradiance per second is too short to get a meaningful treatment time, so we will convert irradiance from one second to one minute.
To get irradiance per minute, multiply irradiance by 60 seconds:
(50 mW/cm^2 per second @ 6 inches x 60 seconds per minute) = 3,000 mW/cm^2 per minute @ 6 inches
Our original irradiance was 50 mW/cm^2 at 6 inches (our arbitrary distance for the sake of example) per second.
Our new irradiance delivers the exact same energy, but per minute: 3,000 mW/cm^2 at 6 inches per minute
Treatment Time Calculation Step 2: Derive Joules (Fluence) from Irradiance
Now we know that 3,000 milliwatts of photons are moving to the sq. cm. spot per minute.
That’s the rate of delivery, but how many photons did we deliver?
To make a dose, we need to know how many photons we’re delivering.
According to the science, the best dosage is between 5 and 60 joules.
Joules is watts per second of photon energy.
Since we don’t get enough energy in a second to do anything meaningful, we will use our conversion to minutes we did above, and calculate for joules per minute.
That’s fluence. We now know the amount of energy at a given sq. cm.
We’re already in minutes, but we are still using milliwatts and not watts.
To convert from milliwatts to watts, divide the irradiance by 1,000.
3,000 mW/cm^2 at 6 inches per minute / 1,000 milliwatts per watt = 3 joules per minute
Are you still with me? We’re done.
We now know that 50 mW/cm^2 at our arbitrary-for-the-sake-of-example distance of 6 inches per second works out to 3 joules per minute at 6 inches.
Treatment Time Calculation Step 3: Derive Minutes per Session
Now we can calculate how many minutes of treatment it takes to get our target joules.
Let’s say you want to go for a 5 joules dose.
How many sets of 3 joules do you need to get 5 joules?
Divide the target joules by the joules per minute to get the treatment time.
- 5 joules target dose / 3 joules per minute = 1.67 minutes treatment time
- What is .67 of a minute?
- .67 of a minute x 60 seconds per minute = 40 seconds
The treatment time is 1 minute 40 seconds from 6 inches to deliver 5 joules.
Summary of Treatment Time Steps
Now let’s put it altogether so you have this in one place:
- Irradiance per second: 50 mW/cm^2 at 6 inches
- Irradiance per minute: 50 mW/cm^2 at 6 inches x 60 seconds per minute = 3,000 mW/cm^2 per minute at 6 inches
- Joules: 3000 mW/cm^2 per minute at 6 inches/ 1,000 to convert milliwatts to watts = 3 joules per minute at 6 inches
- Joules Target Dose: 5J
- Treatment Time: 5 joules target / 3 joules per minute at 6 inches = 1.67 minutes
- .67 of a minute in seconds is .67 x 60 = 40.2 seconds
- Treat for 1 minute 40 seconds at 6 inches to get 5 joules.
Now throw that all out and use fluence to calculate treatment time.
Why Fluence Eats Irradiance for Breakfast
To start with a confession, it is true that Mito Red Light uses the same meter as their competitors to state irradiance.
If they use the wrong meter, don’t they severely overstate irradiance?
Yes, they do, and they say as much on their product pages.
The solar meter part is true. But don’t worry, I promise that Mito Red Light is the hero in this story.
On their product pages, Mito Red Light advises customers not to use irradiance to calculate dosing.
Here is the fluence, they say. Use this certified value that is not inflated to calculate treatment time.
I understand why Mito Red Light includes the inflated irradiance values. They do it for the same reason almost all other vendors do it.
The average consumer would not understand the nuance that it’s taking me 3,000 words to explain to you.
The average consumer would never read an article like this one you’re reading right now.
The average consumer sees 50 mW and 150 mW and assumes that 150 mW is better. End of story. The average consumer buys 150 mW because it must be big, strong, and powerful.
Session time is inversely related to irradiance. A very large irradiance has a smaller session time. And inflated irradiance has an abnormally short session time that might not deliver enough photons to make any difference.
Inflated irradiance leads to a short session time that might not deliver a therapeutic photon dose.
But Mito Red Light also publishes product certified fluence values for dosing. And just like that, dosing becomes easy, honest, and effective.
Fluence is all we need. With fluence, it’s crazy easy to calculate treatment time.
With fluence, we can rely on vendor values because there’s no pressure to inflate the numbers.
We can reliably calculate treatment times using fluence values.
How to Calculate Treatment Time Using Fluence
Irradiance is power delivered to the target. Fluence is the energy delivered to the target. Irradiance is a rate of photon flow. Fluence is a quantity of photon delivery.
It’s also crazy how much easier it is to calculate a treatment time with fluence than it is with irradiance.
Obtain the Fluence Value
Mito Red Light includes fluence values with their specifications.
Go to any product page to get this value.
Let’s use a real world example.
How to Get 5 Joules from a 2.2 J/minute/cm^2 Fluence Light
The smallest fluence amongst the panels is the MitoPRO 300 tabletop with a fluence of 2.2 joules per minute per sq. cm. We have to assume the joules is from a distance that we get from the irradiance. The irradiance is 6 inches, so the joules is 6 inches. To sum up:
The MitoPRO 300 has a fluence of 2.2 joules per sq. cm. per minute at 6 inches.
OK we have everything we need to calculate a dose:
- Target dose: 5 joules
- Distance from lamp to target: 6 inches
- Joules per cm^2 per minute:2
Given a target joules of 5, a distance of 6 inches, and a fluence of 2.2J/cm^2/minute, what is the treatment time?
It is, simply, target joules divided by fluence, or 5/2.2 = 2.27 minutes (2m 16 seconds).
THAT’S IT. We’re done calculating treatment time.
The treatment time for a 5 joules dose from a 2.2 fluence device is 2 minutes, 16 seconds.
How to Get 60 Joules from a 2.2J/cm^2/second Fluence Light
What if we want a large dose using the MitoPRO 300 with its 2.2J/cm^2/min. fluence. How long would that take?
The fluence is still 2.2 joules sq. cm. per minute from 6 inches.
The dose is 60 joules.
Divide the fluence by joules per cm^2 per minute to get the treatment time: 60/2.2 = 27.27 minutes (27m 16s).
The treatment time for a 60 joules dose from a 2.2 fluence device is 27 minutes, 16 seconds.
How to Get a 5 Joules Dose from a 2.8J/cm^2/minute Fluence Light
Now let’s do the same calculations for the most powerful Mito Red Light based on fluence.
The MitoRED MitoMEGA fluence is 2.8 joules per sq. cm. per minute at 6 inches.
The target dose is 5 joules.
- Target dose: 5 joules
- Distance from lamp to target: 6 inches
- Joules per sq. cm. per minute:8
To get treatment time, divide the target joules by the joules per sq. cm. per minute:
5 joules / 2.8 joules per sq. cm. per minute = 1.79 minutes (1m 47 seconds).
The treatment time for a 5 joules dose from a 2.8 fluence device is 1 minutes, 47 seconds.
Calculate a 60 Joules Dose at 6 Inches from a 2.8J/cm^2/minute Fluence
Now let’s calculate the time per treatment to get 60 joules from a 2.2 fluence deivce.
- The fluence is 2.8 joules per sq. cm. per minute at 6 inches.
- The target joules is 60
Divide target joules by joules per sq. cm. per minute to get treatment time:
60 joules / 2.8 joules per cm^2 per minute = 21.42 minutes (21m 25 seconds)
The treatment time for a 60 joules dose from a 2.8 fluence device is 21 minutes, 25 seconds.
Put it all Together: Treatment times for the Least and Most Powerful Lights
How much difference is there between the least and most powerful Mito Red Light device?
Here are the calculations for treatment times we just did.
We calculated treatment time for:
- 2 fluence to deliver 5 joules: 2 min 16 s
- 2 fluence to deliver 60 joules: 1 m 47 s
- 8 fluence to deliver 5 joules: 27 m 27 s
- 8 fluence to deliver 60 joules: 21 m 25 s
| Treatment Time for 5J and 60J using the Lowest and Highest Fluence Mito Red Light Devices | Â | Â |
| Â | 5 Joules Treatment Time | 60 Joules Treatment Time |
| MitoPRO 300 2.2 fluence |
2m 16s (136s) | 27m 27s (1647s) |
| MitoRED MitoMEGA 2.8 fluence |
1m 47s (107s) | 21m 25s (1285s) |
| Difference | 29 seconds | 6m 2s (362s) |
The MitoPRO takes 29 seconds longer than the MitoRED to deliver a 5 joules dose.
The MitoPRO takes 6 minutes 2 seconds longer than the MitoRED to deliver a 60 joules dose.
The MitoRED MitoMEGA is faster than the MitoPRO 300.
A big device like the MitoMEGA has more bulbs to deliver more photons, so it’s going to deliver a faster session.
But the bigger point is that even if one device has a 2.2 fluence and another has a 2.8 fluence, the 2.8 fluence gives you a 6 minute faster session when you’re going for 60 joules.
When you go for fewer joules per session, the advantage starts to disappear. By the time you get to 5 joules, the more powerful MitoMEGA saves you a whole 29 seconds.
If you’re going to a do lots of 60 joules sessions, then you’ll save a lot of 6 minute chunks getting the faster device.
But going for smaller doses, the amount of time saved is not that significant.
Conclusion
Fluence is a superior value to irradiance when calculating red light therapy treatment times.
Irradiance is usually inflated.
Vendors should display fluence per minute (but not per cm. sq.) and explicitly state the distance at which that fluence value is relevant.
There is very little difference between the treatment times of Mito’s least powerful and most powerful devices.
I would not use irradiance or fluence as a metric when deciding which Mito Red Light to buy unless I planned to do 40J, 50J and 60J dosing on a regular basis.
Irradiance is a huge problem in red light therapy shopping. One cannot trust the irradiance values manufacturers give because so many vendors use the wrong meter type to measure light delivery. Mito Red Light now gives us fluence, a solid way to measure a device’s power.
