Red light therapy wavelengths and irradiance explained
Every red light panel lists wavelengths in nanometers and a power figure in mW/cm². Those two numbers are most of what separates a $150 panel from a $1,500 one, and most of what separates a dose that does something from one that doesn't. Here's how to read them.
Wavelengths: which ones and why
| Wavelength | Band | Penetration | Used for | Where you see it |
|---|---|---|---|---|
| 630 nm | Red, visible | Shallow: skin surface | Skin tone, fine lines, wound healing | Common in face masks |
| 660 nm | Red, visible | Skin and just below | Skin, hair, superficial tissue; the most-studied red wavelength | Standard on nearly all panels |
| 810 nm | Near infrared, invisible | Deeper: muscle, joints | Brain and tissue studies often used 810 | Premium panels, some clinical devices |
| 830 nm | Near infrared | Deep | Skin and wound healing research | Some premium panels and masks |
| 850 nm | Near infrared | Deep: muscle, joints | Recovery, pain; the most common NIR on consumer panels | Standard on nearly all panels |
| Others (480 blue, 1060+) | Varies | Varies | Blue: acne. 1060+: niche | Marketing more than evidence on most consumer devices |
The research clusters around 630-680 nm (red) and 800-880 nm (near infrared). A panel with 660 and 850 covers both and is the sensible default. Multi-wavelength panels that add 630, 810 and 830 are fine but not clearly better; a panel listing seven wavelengths isn't delivering seven doses, it's splitting its LEDs seven ways.
Irradiance: the number brands fudge
Irradiance is power density at the skin, in milliwatts per square centimeter. It falls off fast with distance, so the figure only means something with a distance attached. Honest listings look like "50 mW/cm² at 6 inches." Ones to distrust: a single big number with no distance, a number measured at the LED surface ("over 200 mW/cm²"), or figures taken with a solar power meter, which over-reads LEDs by two to four times.
| Distance | Typical mW/cm² (good panel) | Note |
|---|---|---|
| At the LED surface | 150-250+ | Meaningless for dosing; nobody sits touching the panel |
| At 3 inches | 80-120 | Realistic for a face mask or a panel held close |
| At 6 inches | 40-80 | The usual comparison distance; good panels land here |
| At 12 inches | 15-35 | Full-body distance; needs longer sessions |
| At 24 inches | 5-12 | Too far for most protocols |
Turning that into a dose
Dose is in joules per square centimeter: J/cm² = (mW/cm² ÷ 1,000) × seconds. Skin studies mostly used 3-10 J/cm²; deeper tissue and pain studies used 10-60 J/cm². Example: a panel delivering 50 mW/cm² at 6 inches gives 3 J/cm² a minute, so a 10-minute session is about 30 J/cm², which covers both ranges. That's why 10-20 minutes at 6-12 inches is the common recommendation. More isn't better; most studies show a window where very high doses do less, not more.
Other specs that matter
- Coverage area. A 12 x 8-inch panel treats a face or a knee. Full-body means a 36-inch or taller panel, or two.
- Flicker. Cheap drivers pulse the LEDs at mains frequency; some people get headaches. Good brands advertise "no flicker" and mean it.
- Pulsing modes. Marketed as a feature; the evidence is mixed and continuous output is the default in most studies.
- EMF. As with saunas, low at the body position is easy to achieve and worth checking.
- Beam angle. Narrow lenses (30°) concentrate light at close range; wide (60-90°) spreads it, lowering irradiance but widening the treated area.
- Third-party measurements. Brands that publish independent irradiance tests (Mito, PlatinumLED, Hooga among them) are telling you something about their numbers.
Red flags on a product page
- Irradiance with no distance stated.
- "Medical grade" with no FDA listing or clearance number.
- Seven or more wavelengths on a $200 panel.
- Claims of fat loss, "detox," or curing anything.
With the numbers decoded, our panel comparison and face mask guide are easier to use. If you're deciding between buying a panel and booking sessions, home vs clinic runs that math.
General education, not medical advice.