Know what the
numbers mean.
An LED count is just one detail. A useful device specification also describes the light emitted, the power reaching the measurement surface, and the duration of exposure.
What does wavelength mean for an LED mask?
Wavelength is measured in nanometres (nm). Red, blue, and near-infrared describe broad ranges; an exact peak and tolerance are more informative than a colour label. A nominal manufacturer value and a measured spectrum should be labelled separately.
What is irradiance (mW/cm²)?
Irradiance is optical power per unit area, often reported in milliwatts per square centimetre (mW/cm²). A usable comparison specifies the measurement distance, device mode, instrument, and whether the value is a peak or area average.
Electrical battery power, diode count, and optical irradiance are different measurements.
How is LED light dose (J/cm²) calculated?
For constant irradiance, radiant exposure is irradiance multiplied by exposure time, with compatible units.
For example, a constant 20 mW/cm² for 600 seconds gives 12 J/cm² at the measurement surface. This is a unit-conversion example, not a recommended treatment dose or a measurement of any listed mask.
When a device changes modes or pulses during a session, the calculation needs time-resolved or average irradiance rather than an isolated peak.
Why do measurement conditions matter?
Fit and distance influence the light reaching a surface. Compare data obtained with matching conditions, and keep differences visible. Laboratory output measurements do not by themselves show a clinical outcome.
Put the specifications side by side