Red Light Therapy Dose Calculator
Within the commonly studied 10-60 J/cm² range.
How to use it
Two inputs. First, the irradiance your panel delivers at the distance you sit, in mW/cm², taken from a figure that states its instrument and distance; the irradiance labels guide explains which figures qualify. Second, the length of the session in minutes. The result is the energy delivered to each square centimeter of skin facing the panel, in J/cm². The calculator does not model distance: irradiance falls as you move back, so use the figure published for the distance you actually use, or a closer figure only if you sit at that distance.
A worked example, and why the method matters
The BlockBlueLight PowerPanel MID publishes both a solar meter figure, 158 mW/cm² at 6 inches, and a spectrometer figure, 61 mW/cm² at the same distance (both from the brand's own dual disclosure, recorded in the claimed vs measured table). A 10 minute session at 6 inches works out to 94.8 J/cm² on the solar meter number and 36.6 J/cm² on the spectrometer number. The panel did not change; the instrument did. Only the spectrometer figure belongs in the calculator.
Session length for a target dose
Minutes needed to reach a given dose, from the same formula (minutes = dose × 1000 ÷ irradiance ÷ 60). Read across for your panel's spectrometer irradiance at your distance.
| Irradiance (mW/cm²) | 10 J/cm² | 20 J/cm² | 40 J/cm² | 60 J/cm² |
|---|---|---|---|---|
| 25 | 6.7 min | 13.3 min | 26.7 min | 40 min |
| 50 | 3.3 min | 6.7 min | 13.3 min | 20 min |
| 75 | 2.2 min | 4.4 min | 8.9 min | 13.3 min |
| 100 | 1.7 min | 3.3 min | 6.7 min | 10 min |
| 150 | 1.1 min | 2.2 min | 4.4 min | 6.7 min |
What the number does not tell you
Dose per square centimeter says nothing about how much of the body the panel covers or which wavelengths carry the energy; those are separate fields in the panel database, and the wavelength guide covers what each band is used for. The 10 to 60 J/cm² range is where most published protocols sit, not a prescription: the studies on each evidence page state the dose they used, and that is the figure to match for a given goal.
Remember the measurement method
If your panel only publishes a solar meter or method-unstated figure, halve it as a working assumption before calculating, and check whether a spectrometer test exists. See spectrometer vs solar meter.
For a real-world reference point, the 2013 Lanzafame male hair-growth RCT used 67.3 J/cm² per 25-minute session, delivered every other day for 16 weeks; see our review of that trial for how the dose and schedule connect to its result.
Not every trial reports a usable dose: the 2012 Zhao whole-body sleep trial names a 30-minute nightly session over 14 nights but never states a wavelength or irradiance, so there is no dose from that paper to plug in here; see our review of that trial for what it does and does not report.
The 2025 diabetic neuropathy trial used 3.1 J/cm² delivered over 9 minutes to the dorsal and plantar foot surfaces, daily for ten days; see our review of that trial for what it measured and the gap between its laser protocol and a home panel.
Exercise-performance trials tend to report total power rather than an irradiance density: a 2015 meta-analysis found the most consistent pre-exercise results at 50 to 200 mW of total optical power and 5 to 6 J per irradiated point, figures that cannot be entered directly into this calculator without knowing the treated area; see our review of that meta-analysis for why total power and irradiance density are not the same number.
The irradiance figure you enter here is only accurate at the distance it was measured, almost always 6 inches for the panels in this site's database. If you plan to sit farther away, what distance to sit from a panel covers how to pick a working distance by goal, and the inverse square law explainer covers why a flat panel's output does not fall off with distance the way a simple point of light does, so a number calculated for a longer distance should be treated as an estimate rather than a precise dose.
To see how much session length actually changes across the strongest verified panels, this site's ranking of the highest method-labeled irradiance figures works out the session time each one needs to hit a common 20 J/cm² target.
New to dosing terms or this calculator's inputs? This site's FAQ answers the most common questions on session length, frequency and irradiance in a few sentences each, with a link to the fuller page behind each answer.
Whole-body dosing has its own trial to reference: a triple-blinded fibromyalgia RCT delivered 25.2 J/cm² per 20-minute session in a bed that surrounds the body from multiple angles at once, a geometry no single panel reproduces; see the fibromyalgia evidence page for that trial alongside the rest of the condition's literature, and treat front and back of the body as two separate sessions when estimating a comparable dose on a panel.
Two common claims about this formula's inputs are checked directly in this site's myths-checked guide: that a higher-wattage panel always delivers more dose, and that distance from the panel does not matter. Neither holds up against the irradiance and inverse-square-law figures this calculator actually runs on.
Point-applied laser trials use a different dosing convention entirely: the 2014 fibromyalgia RCT delivered 4 J/cm² to 18 individual tender points, three times a week for four weeks, a per-point figure that cannot be typed into this area-based calculator without deciding what one panel-illuminated "point" corresponds to; see the study review of that trial and the 2019 meta-analysis for the full dosing gap.
This calculator gives you the time for one placement of one device. Treating more than one area in a session multiplies that time by the number of placements your device needs, since a small device covers less area per placement than a wide one; our targeted device vs full panel guide works out that multiplication using real irradiance figures from a small, a mid-size and a full-body panel in this database.
The point-dose tables published by WALT (the World Association for Laser Therapy) use a different unit than this calculator: a fixed number of joules delivered to one treatment point with a laser, not an irradiance over an area. See WALT dosing recommendations explained for how one WALT-dosed knee osteoarthritis trial applied that convention and why the joule-per-point figure cannot be typed into this calculator without a stated spot size.
Which dose to aim for depends partly on the tissue: a 2018 parameters review found muscle, brain, heart and nerve tended to respond to lower doses than skin, tendon and cartilage, as covered in our study review of that paper.