A red light therapy device is only as good as the protocol you use with it. Most users either under-dose (too far away, too short) or over-dose (too close, too long) — and wonder why they're not seeing results. This guide gives you the exact distance, time, and frequency for every common use case.
The Dosage Math (Made Simple)
Red light therapy dosage is measured in joules per square centimeter (J/cm²). The formula is simple:
Dose (J/cm²) = Irradiance (mW/cm²) × Time (seconds) ÷ 1000
For example, if your panel delivers 100 mW/cm² at 6 inches and you use it for 5 minutes (300 seconds):
Dose = 100 × 300 ÷ 1000 = 30 J/cm²
The therapeutic dose for most conditions is 4–15 J/cm² per session. Below 4 J/cm², you're not delivering enough energy for cellular effects. Above 15 J/cm², you hit the "biphasic dose response" — more light actually reduces the effect.
The good news: most modern panels deliver 80–115 mW/cm², which means you only need 1–3 minutes per treatment area to hit the therapeutic dose. The bad news: most users treat for 10–20 minutes, thinking "more is better" — they're over-dosing and getting fewer results than they would with shorter sessions.
Distance vs. Irradiance Chart
Irradiance drops off rapidly with distance, following the inverse-square law: double the distance, and you get one-quarter the irradiance. Here's a chart for a typical 100 mW/cm² panel (like the MitoMAX):
| Distance | Irradiance | Time for 10 J/cm² | Time for 15 J/cm² |
|---|---|---|---|
| 3 inches | ~140 mW/cm² | ~70 seconds | ~105 seconds |
| 6 inches | ~100 mW/cm² | ~100 seconds (1.7 min) | ~150 seconds (2.5 min) |
| 12 inches | ~60 mW/cm² | ~170 seconds (2.8 min) | ~250 seconds (4.2 min) |
| 18 inches | ~40 mW/cm² | ~250 seconds (4.2 min) | ~375 seconds (6.3 min) |
| 24 inches | ~25 mW/cm² | ~400 seconds (6.7 min) | ~600 seconds (10 min) |
Notice how quickly irradiance drops: at 24 inches, you need 4x the session time to get the same dose as at 6 inches. For most conditions, 6–12 inches is the optimal distance — close enough for therapeutic irradiance, far enough for reasonable coverage area.
Session Time by Condition
Here's the recommended session time per treatment area (at 6 inches from a 100 mW/cm² panel):
| Condition | Target Dose | Session Time |
|---|---|---|
| Wrinkles / Anti-aging | 4–6 J/cm² | 1–2 minutes |
| Acne | 4–8 J/cm² | 1–2 minutes |
| Wound healing | 5–10 J/cm² | 1–2 minutes |
| Eczema / Psoriasis | 5–8 J/cm² | 1–2 minutes |
| Mild joint pain | 8–12 J/cm² | 2–3 minutes |
| Severe joint pain / Arthritis | 10–15 J/cm² | 2–3 minutes |
| Muscle recovery | 8–12 J/cm² | 2–3 minutes |
| Tendonitis | 10–15 J/cm² | 2–3 minutes |
| Plantar fasciitis | 10–15 J/cm² | 2–3 minutes |
| Hair regrowth (LLLT helmet) | Per manufacturer | 20–25 minutes |
These times are per treatment area. If you're treating your whole face, that's one area. If you're treating both knees, that's two areas — treat each one separately.
How Often Should You Treat?
Frequency matters as much as dose. Here's the general guidance:
- Skin concerns (wrinkles, acne, etc.): Daily or 5–6x per week
- Pain relief: Daily for acute pain, 3–5x per week for chronic pain
- Hair regrowth: Every other day (per iRestore protocol)
- Muscle recovery: After intense workouts (3–5x per week)
- General wellness: 3–5x per week
Daily use is safe for most conditions, but giving your body 1–2 rest days per week can prevent diminishing returns. Listen to your body — if you feel fatigued, take a day off.
Condition-Specific Protocols
For Wrinkles
Sit 6–8 inches from your panel for 2 minutes per face area (forehead, cheeks, around eyes, around mouth). Total session: 8 minutes for full face. Daily or 5–6x per week. See our wrinkle protocol.
For Knee Pain
Position the panel 6 inches from your knee for 3 minutes. Treat both sides of the knee (front and back). Daily for acute pain, 3–5x per week for chronic. See our knee pain guide.
For Lower Back Pain
Sit with your back 6 inches from the panel for 3 minutes. If you can't sit close, lie on the floor with the panel propped above you. Daily for acute flare-ups, 3–5x per week for chronic. See our back pain guide.
For Hair Regrowth
Use an LLLT helmet (like the iRestore) for 25 minutes per session, every other day. Don't use a panel for hair regrowth — the wavelength and irradiance aren't optimal. See our hair loss buying guide.
For Muscle Recovery
Use the panel for 3–5 minutes per muscle group immediately after training. Treat both sides of the muscle (front and back). See our muscle recovery guide.
Signs You're Over-Dosing
Yes, you can over-dose red light therapy. The "biphasic dose response" means that beyond the optimal dose, more light produces LESS effect, not more. Signs you're over-dosing:
- Skin feels hot or irritated after sessions (not just pink from blood flow)
- No improvement after 4–6 weeks of consistent use
- Headaches or fatigue after sessions
- Plateau in results after initial improvement
If you're experiencing any of these, try halving your session time for 2 weeks and see if results improve. Most users are surprised to find that less is more with RLT.
Frequently Asked Questions
The Best Panel for Dosage Control
The MitoMAX 2.0 publishes real irradiance specs, making dosage calculations accurate.
Check on Amazon →