What the mask numbers mean.

Wavelength (nm)

The colour of light, in nanometres. On this site, blue is 400–499 nm, green 500–569 nm, yellow 570–619 nm, red 620–699 nm and near-infrared 700 nm or above. Near-infrared is not visible as colour. Brands usually publish a nominal wavelength; actual LEDs emit a spread around it, and some brands also publish measured peaks.

In the comparison, four of five masks list near-infrared and four list blue light. See the wavelength map

LED count

The number of light-emitting diodes reported by the manufacturer. Some brands count multi-chip bulbs differently from single LEDs, so the same physical design can be described with different totals. A higher count does not establish more even coverage, higher output or better results.

Reported counts range from 132 to 750 across the five masks.

Irradiance (mW/cm²)

Optical power arriving per square centimetre of surface, usually given in milliwatts per square centimetre. It depends on distance from the LEDs, mode, wavelength mix, pulsing (duty cycle) and where it was measured. Brands rarely publish these conditions, so figures from different brands are not a laboratory comparison.

Three of the five masks have a published figure, from 26.9 to 50 mW/cm². Dr. Dennis Gross FaceWare Pro and Shark CryoGlow had no numeric irradiance on the checked page.

Dose or fluence (J/cm²)

Energy delivered per square centimetre over a session. For constant output it is irradiance multiplied by time: mW/cm² × seconds ÷ 1000 gives J/cm². Because irradiance conditions differ by brand and mode, Estimates on device pages multiply reported irradiance by session time; these are calculations from claims, not measurements.

Session duration

The treatment time the manufacturer recommends for one use. It may vary by programme or mode. Longer sessions are not inherently better; follow the device’s manual and use limits.

FDA cleared

In the US, a 510(k) clearance means the FDA found a device substantially equivalent to a legally marketed predicate device for a stated use. It is different from FDA approval, and it does not compare one cleared device with another. Claims here keep their source status, such as “manufacturer claim” or “as reported by LED Mask Specs”.

CE and UKCA marking

A declaration that a product meets the EU (CE) or Great Britain (UKCA) rules that apply to it. A mask may be CE marked as consumer electronics (for example under the Low Voltage and RoHS directives) rather than as a medical device under the EU Medical Device Regulation. The marking alone does not describe performance.

Reference price

A price seen in a named source on a given date, kept in its original currency. Reference prices are not current offers, are not converted between currencies, and may include older baseline figures that were not revalidated.