Red light therapy, minus the jargon

How much red light is the right amount?

Short answer: red light therapy works on a dose, not a timer. Dose (J/cm²) = power density (mW/cm²) × seconds ÷ 1,000. Research summaries put skin goals around 2–10 J/cm² and deeper tissue around 10–70 J/cm². Past the sweet spot, results can fade rather than improve. Because power drops quickly with distance, where you stand matters as much as how long you stay.

Last checked: 2026-10-26 · Educational only, not medical advice · No affiliate links

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Red light therapy dosing: the Goldilocks ruleJ/cm² without the jargon. The formula, skin vs deep bands, distance, and signs of too much. Dosing cheat sheetThe whole thing on one printable page. LED face masks compared (2026)Fit, power and wavelengths that matter, plus the dose math most mask reviews skip. Red light panels: how to choose (2026)Dollars per usable mW/cm², input vs output watts, coverage, EMF, flicker and warranty.

660 vs 850 nm by goalComing soon.

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What this site is (and isn't)

Red Light Guide explains red and near-infrared light therapy in plain English: dose, wavelength, distance and what to check before you buy. We summarise published research and well-known reviewers' findings, and we say so on every page. We don't sell devices, we don't claim light cures anything, and nothing here replaces advice from your clinician.

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One printable page: the dose formula, skin vs deep bands, the distance rule and the “too much” warning signs. Plus a short, occasional email with one practical tip. No spam.

By signing up you agree we email you the cheat sheet and occasional Red Light Guide tips. Double opt-in — confirm the email we send. Unsubscribe anytime. You can also read the cheat sheet online. Educational only, not medical advice.