What to look for in the specifications

Why specifications matter

Wavelength tells you the colour of light. It doesn't tell you how much light reaches your skin, which is what studies vary when they test effects. A 2025 analysis of 27 LED skin studies found doses ranged from 0.1 to 126 J/cm², more than a thousandfold, often without explanation, and that none of the studies measured their own device's output; all relied on the maker's figures [1].

So published specifications are the only way to compare masks on paper, and even then they're the brand's claims.

Light output (irradiance)

Irradiance is the light power landing on each square centimetre of skin, given in milliwatts per square centimetre (mW/cm²). It falls quickly with distance, so the same LEDs give a lower figure if the mask sits further from the skin.

Where was it measured?

At the LED surface, or at a stated distance such as where the skin sits? A figure "at 0 mm" will be higher than at the skin.

Per colour or combined?

Some brands give one figure per colour, others add colours together. A "128 mW/cm²" total for two colours is about 64 each.

Average or peak?

Light is strongest directly under an LED and weaker between them. A single figure may be the peak.

Light output or electrical power?

Electrical power going into the LEDs (watts) isn't the light coming out. The 2025 analysis found studies often didn't say which they meant [1].

For scale, the two recent sham-controlled mask trials used about 6.4 mW/cm² [2] and up to 10 mW/cm² per colour [3]. A higher figure isn't shown to work better, and higher output can feel warm.

Show masks that publish light output

Dose (fluence)

Dose is the total light delivered in a session, in joules per square centimetre (J/cm²). It's irradiance multiplied by time:

For comparison, a well-known study of red light used about 9 J/cm² per session, twice a week [4], and one recent mask trial about 8 J/cm² [2]. Clinic wrinkle studies have used far more [5]. There's no agreed "right" dose for home masks.

Where a brand publishes irradiance and session time but no dose, our listings show a calculated dose, labelled "Calculated by Luma Index". It inherits any uncertainty in the brand's irradiance figure.

LED count

19 of 21 masks publish an LED count, and 6 have sources that disagree on it. The usual reason is what's being counted:

• Chips or packages: one LED package can hold two or three chips of different colours. Shark's FDA filing describes 160 "tri-wick" packages, which is 480 LEDs; reviews quote both numbers. See the Shark listing.
• Per colour or total: The Light Salon describes "56 dual-chip LEDs", 56 red plus 56 near-infrared. Reviews quote 56, 57 and 112. See the listing.
• "More LEDs" claims: comparisons like "2× the industry average" rarely say what they're compared with.

LED count says more about coverage and spacing than strength. A mask with fewer, stronger LEDs held close to the skin can deliver more light than one with many weak ones.

Sessions, frequency and power

• Session length ranges from 3 to 30 minutes across our directory. A short session may simply mean higher output, so compare dose rather than minutes.
• Frequency: anything from daily to two or three times a week. One trial found twice a week worked as well as three times [2]. Follow the maker's instructions; longer or more frequent sessions aren't shown to help more.
• Battery and charging: 11 masks publish a charge time. Check how many sessions a charge lasts and whether the mask works while plugged in.
• Weight: 169–1810 g where published. Weight and strap design affect whether you can move around.
• Timer and shut-off: check there's an automatic timer, so you can't overdo a session by accident.

Warranty, returns and the manual

These are specifications too. A two-year warranty, a clear returns policy and a manual you can read before buying tell you about the company behind the mask. The manual is usually the best source for modes, safety warnings and the safety standards the mask was tested to. See the labels guide for what those standards mean.

What brands leave out

Our listings check 12 key facts. This is how many of the 21 masks in our directory publish each one. It counts transparency, not quality.

Sort masks by key facts published

Questions to ask

1. What's the irradiance for each colour, and at what distance, with what instrument?
2. Is that figure an average across the mask or the peak under one LED?
3. What dose does one session deliver?
4. Does the LED count mean chips, packages or colours combined?
5. How long is a session, how often, and is there an automatic timer?
6. Can I read the manual before buying?

Compare masks side by side Wavelengths explained

Sources

1. Methodological issues in visible LED therapy dermatological research and reporting. Grimes DR, PLOS ONE 2025;20(9):e0332995.
2. Role of photobiomodulation application frequency in facial rejuvenation: randomized, sham-controlled, double-blind, clinical trial. Bragato EF, … Fernandes KPS (10 authors), Lasers in Medical Science 2025;40(1):170.
3. Clinical study to evaluate the efficacy and safety of home-used LED and IRED mask for crow's feet: a multi-center, randomized, double-blind, sham-controlled study. Park SH, Park SO, Jung J-A, Medicine (Baltimore) 2025;104(7):e41596.
4. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Wunsch A, Matuschka K, Photomedicine and Laser Surgery 2014;32(2):93–100.
5. Unlocking the Power of Light on the Skin: A Comprehensive Review on Photobiomodulation. Hernández-Bule ML, Naharro-Rodríguez J, Bacci S, Fernández-Guarino M, International Journal of Molecular Sciences 2024;25(8):4483.

Directory figures are counted from our 21 UK mask listings and update as listings change. Summaries are written by Luma Index. See the research page for the full evidence library, including each study's limitations.