Turn your panel's irradiance and your session length into an energy dose in joules per square centimeter, or work out how long a session takes to reach a target dose. Part of our free calculators and tools.
How it works
- Energy dose (radiant exposure) equals irradiance multiplied by time. With irradiance in mW/cm² and time in seconds: dose in J/cm² = mW/cm² × seconds ÷ 1,000.
- Time for a target dose = target J/cm² × 1,000 ÷ irradiance in mW/cm².
- Irradiance falls quickly with distance, so use the value your panel maker lists for the distance you actually use, or a reading from a light meter.
- Light therapy devices are sometimes labeled with inaccurate parameters, so verify the stated output independently where you can. The optional reduction field lets you account for a gap.
- This tool calculates energy only. It does not recommend a dose for any purpose.
Sources
- IUPAC Gold Book: radiant exposure (definition H = E × t)
- Huang, Chen, Carroll and Hamblin, Biphasic dose response in low level light therapy (Dose-Response, 2009)
- Khan and Arany, Dosimetry for photobiomodulation therapy (Annals of Translational Medicine, 2016)
- Enwemeka, The relevance of accurate comprehensive treatment parameters in photobiomodulation (Photomedicine and Laser Surgery, 2011)
Sources last checked October 13, 2026. For information only.