Red light panel listings all look broadly similar: a run of impressive-sounding figures with units attached. Most buyers have no way to tell which of them matter. This is a line-by-line guide to what each number means, which ones are load-bearing, and where the industry consistently overstates.
The quick version
| Spec | Useful? | Why |
|---|---|---|
| Irradiance with distance and instrument | Yes — the main one | What actually reaches your skin |
| Wavelengths in nm | Yes | Determines what the light does |
| Panel dimensions | Yes | Determines coverage per session |
| Irradiance with no distance | No | Unfalsifiable |
| LED count | Barely | A component count, not performance |
| Wattage | Barely | Power drawn, not light delivered |
| "Up to" anything | No | Best case, not typical case |
| EMF at 4–6 inches | Marginal | Almost always 0.0 — no discrimination |
| Rated LED lifespan | Marginal | Never the failure point in practice |
1. Irradiance — and the three questions
Irradiance is the energy reaching your skin, in mW/cm². It is the number panels are sold on and the one most easily overstated, because the figure depends entirely on how it was taken.
Ask three questions of any irradiance claim:
What is the figure? A number with no units or no context is not a specification.
At what distance? Irradiance falls off sharply with distance. A reading at the LED surface is dramatically higher than one where a person would stand. Six inches is 15cm, so figures quoted at those two distances are directly comparable — a figure at 30cm is not.
On what instrument? This is the one almost nobody asks, and it is where the factor-of-two lives. A solar or photovoltaic meter reads roughly twice as high as a spectrometer on LED light. The spectrometer is the correct instrument.
What the gap looks like in practice
You do not have to take our word for it — several brands publish both figures themselves. BlockBlueLight lists its PowerPanel MEGA at "up to 167mW/cm²", then states an average of 87 mW/cm² at the same distance from spectrometer readings. On the smaller PowerPanel PRO the same two numbers are 160 and 68.
Look at what happens across those two models. The LED count doubles from 150 to 300. The honest spectrometer figure climbs from 68 to 87. The headline solar figure barely moves — 160 to 167. The big number has stopped measuring anything useful about the panel. It has effectively saturated.
MITO LIGHT publishes 82 mW/cm² on a spectrometer against 145 on a solarmeter at the same 15cm. Same pattern, same ratio.
Every Dermfix RLF panel publishes a spectrometer figure measured at 15cm, on axis, at the centre of the panel, per model — 82 mW/cm² on the compact models up to 92 on the largest. We do not publish a solar-meter number, because it would only make the panels look better than they are.
How much do you actually need?
For home use, a measured 40–100 mW/cm² at 15cm is a sound target. More output mainly shortens the session rather than improving it. A panel claiming 200+ is either quoting a solar meter, quoting a surface reading, or both.
2. Wavelengths
Should be listed in nanometres, not colours. "Red LED" tells you nothing; "660nm and 850nm" tells you what the panel does.
660nm red is absorbed nearer the skin surface. 850nm near-infrared reaches deeper tissue. Those two carry most of the published research and are the baseline to look for. Additional wavelengths add flexibility rather than necessity.
Be wary of wavelength count used as a headline. It is the cheapest specification to increase and the least informative on its own — a panel with eight wavelengths and no honest irradiance figure is worse than one with two and a published measurement.
3. LED count
A component count, not a performance figure. It correlates loosely with panel size and therefore coverage, which is genuinely useful. It does not tell you output.
Compare a 288-LED panel and a 300-LED panel and you learn almost nothing. Compare their measured irradiance at a stated distance and you learn everything.
4. Wattage
Wattage is power drawn from the wall, not light delivered to skin. The conversion between the two depends on LED efficiency, driver quality and thermal management — none of which are on the spec sheet.
Watch for a particular trick: "1500W" style model naming where the actual power consumption is a fraction of that. The number in the model name is often the theoretical maximum of all LEDs at full drive, which is not how the panel runs.
5. Panel dimensions
Genuinely useful, and under-appreciated. Dimensions tell you how much of you gets treated in one session, which is what determines session length. A tall narrow panel and a short wide one with identical LED counts give very different experiences.
Check the height against your own. A 90cm panel does not cover a standing adult.
6. EMF
Almost every panel on the market publishes 0.0 µT at four to six inches. When every device in a category reports the same number, that number is not helping you choose. Worth a glance, not worth weighting.
7. Flicker
Rarely quantified, usually just asserted as "flicker-free". Reasonable to prefer, hard to verify from a listing.
8. Rated LED lifespan
Usually 50,000 to 100,000 hours. At fifteen minutes a session, 50,000 hours is around 200,000 sessions. Both figures are effectively "longer than you will own it", so the difference between them is not a purchasing consideration. Drivers and fans fail before LEDs do, which is why the warranty tells you more than the rating.
9. Certification
The most commonly misread line on any spec sheet. Every panel carries a CE mark of some kind — the question is what it was tested against.
EN 60335-2-27 is the standard covering electrical appliances that expose human skin to optical radiation. It describes what a red light panel actually does to a person. Electrical-safety and electromagnetic-compatibility testing, by contrast, is about the appliance itself.
Reviewing published certification wording across the panels sold into the UK, we could not find another brand naming that standard. What appears instead is bare "CE", CE with a directive rather than a standard, IEC 60601 (the general medical electrical equipment standard), or FDA registration — which is a listing rather than a clearance, and is not a UK requirement in any case.
Dermfix panels are tested and certified to EN 60335-2-27. It is a fair question to put to any brand you are considering, including us.
The one line that is not a spec
Check where the panel ships from. A device dispatched from outside the UK is an import, so UK VAT at 20% becomes payable to the courier on delivery — on a four-figure purchase that is a significant sum arriving after you have already paid. A .co.uk domain does not tell you the answer; the seller's shipping page does.
Our UK buyer's guide shows what each panel on the UK market actually costs once that is accounted for, taken from live checkouts.
A checklist you can use on any listing
- Is there an irradiance figure with a distance attached?
- Is the instrument named, and is it a spectrometer?
- Are wavelengths listed in nanometres?
- Do the panel dimensions cover the area you want treated?
- Is the safety standard named by number, not just "CE"?
- What is the warranty, and does it cover the driver as well as the LEDs?
- Where does it ship from, and is UK VAT in the price shown?
A panel that answers all seven is being straight with you. See how the Dermfix RLF range answers them.
Common questions
What does mW/cm² mean in red light therapy?
Milliwatts per square centimetre — the light energy reaching a given area of skin. It is only meaningful when quoted with the distance it was measured at and the instrument used.
Why do red light panels quote two different irradiance numbers?
Because a solar or photovoltaic meter reads roughly twice as high as a spectrometer on LED light. Some brands publish both. Where only one figure appears and it is unusually high, it is likely the solar-meter reading.
Is a higher LED count better?
Not on its own. LED count is a component count that correlates loosely with panel size and coverage. It does not tell you the output reaching your skin.
Does wattage tell you how strong a red light panel is?
No. Wattage is power drawn from the mains, not light delivered to skin. Model names containing a wattage figure often refer to a theoretical maximum rather than actual consumption.
What certification should a red light panel have?
Look for the standard named by number rather than a bare CE mark. EN 60335-2-27 covers appliances that expose human skin to optical radiation, which is what a red light panel does.
Competitor figures cited are each brand's own published data, checked 19 August 2026. This article is general information about choosing equipment and is not medical advice.