How to Choose a Red Light Therapy Panel

If you compare two panels on a single number, it will almost certainly be irradiance: the light power landing on a surface, written as mW/cm². It is the number used to prove a panel is strong.

It is also close to meaningless on its own, and it is the most consistently misrepresented figure in this category. Usually not through dishonesty. Through omission.

Two panels can both advertise 150 mW/cm² and deliver very different amounts of light. There are three reasons, and each one is a question you can ask.

The Distance It Was Measured At

A reading taken with the meter pressed against the face of the panel is a far larger number than one taken where a person actually sits. Contact readings are not fabricated. They simply do not describe your session.

There is no enforced measurement standard in this industry, which is worth knowing before you assume two numbers are comparable. In practice the useful range to ask about is six to eight inches, because that is roughly where real sessions happen and it is the distance most serious manufacturers report at. What matters is not which number they pick. It is whether they tell you.

Output also falls away quickly as you step back. Manufacturers model this with the inverse square law, which says that doubling the distance leaves you near a quarter of the intensity:

Treat that table as the shape of the problem rather than a promise. Inverse square describes a point source exactly, and a large panel viewed from six inches is not a point source, so a big panel often measures gentler than the pure arithmetic predicts at close range.

This is why you want the manufacturer's own measured figures at several distances rather than a number you calculated. A brand publishing readings at six, twelve, eighteen and twenty four inches has done the work. A brand with one number has not, or would rather you did not look.

The Instrument It Was Measured With

Irradiance can be measured with a spectrometer or with an inexpensive solar power meter, and the two do not agree. Solar meters are built for broad spectrum sunlight, not narrow band LEDs, and pointed at a panel they also collect ambient room light and reflections off the walls. On narrow band LED light a solar power meter over reports by roughly a factor of two against a spectrometer.

So one panel can advertise close to double the figure of an identical panel measured the other way, and nobody has to lie. They simply never say which instrument was used.

What Honest Disclosure Looks Like

One full body panel on the market publishes both figures for the same hardware: 174 mW/cm² at eight inches measured with a solar power meter, and 119.28 mW/cm² at six inches measured with a spectrometer.

Read that twice. The spectrometer figure is taken closer to the panel and is still around a third lower. Neither number is dishonest. But if a rival published only the first and this manufacturer published only the second, the better documented panel would look like the weaker one.

Where on the Panel It Was Measured

Panels are brightest dead center. A single center point figure tells you nothing about what reaches a shoulder or a knee out at the edge, which on a full body panel is exactly the coverage you are paying for. Ask for readings across the surface, not one hot spot.

Panels are increasingly sold on wavelength count. Five wavelengths, seven, ten. More sounds better. Sometimes it is a real design decision. Sometimes it is a way to make a spec sheet look fuller.

Wavelength determines how deeply light travels into tissue, which is the reason panels combine several at all. The band this category works in runs roughly 600 to 1000 nanometers. Below about 600 nm there is not enough penetration to be interesting. Above about 1000 nm a growing share of the energy is absorbed by water and ends up as heat rather than reaching anything.

Two things follow from that table, and they pull in opposite directions, which is why this section exists.

The foundation is red plus near infrared. Nearly every credible panel pairs something around 660 nm with something around 850 nm, because that pairing carries the deepest evidence base. If a panel does not include both, ask why.

Additional wavelengths are not a red flag either. Multi wavelength design is a legitimate engineering choice and combined approaches are actively researched. But there are three things worth understanding before you pay a premium for a longer list:

• They Are Not Interchangeable Units — Blue light and near infrared do fundamentally different jobs. A wavelength count treats them as if they were the same currency, and they are not.
• They Share One Power Budget — Diodes assigned to a fifth or sixth wavelength are diodes not assigned to the two carrying the most evidence. That is a real trade, not a free addition. Ask what share of total output each band represents, because a wavelength listed at two percent of output is closer to a line on the box than a feature.
• The Evidence Behind Each One Varies Enormously — Some bands rest on hundreds of studies. Others are genuinely early. A list treats them as equals.

The Engineering Reality That Defuses a Lot of Marketing

LEDs do not emit a single clean wavelength the way a laser does. They spread roughly twenty nanometers either side of their rating, so an 830 nm and an 850 nm LED overlap substantially, and 850 is often chosen partly because it costs less to source. A brand making a large claim about a twenty nanometer difference is selling you a precision the hardware does not have.

Total Wattage Is Not Output — "1,000W" usually describes power draw, or the sum of the diodes' rated maximums, rather than anything that reaches a body. Diodes are rarely driven at their maximum and a large share of the input leaves as heat. Wattage tells you about your electricity bill. Irradiance at a stated distance, measured with a stated instrument, tells you about the session.

LED Count Is a Proxy, Not a Measure — More diodes across the same area can mean better uniformity. It can also mean more, weaker diodes. Count only means something alongside output and coverage area.

Coverage Area Is the Spec People Forget — A strong panel with a small coverage area means repositioning partway through, which quietly doubles the time the session actually takes. Check the dimensions of the light field, not just the dimensions of the housing.

Beam Angle, Which Almost Nobody Asks About — Lens design decides how much of the light lands on you rather than on the wall behind you. Wide, unfocused beams spread output into the room. Narrower or mixed beam optics keep more of it on target, which is part of why two panels with similar diode counts can behave very differently at the same distance. Ask what the beam angle is and whether the optics are mixed.

Flicker and EMF — Both are marketed heavily and both are reasonable to ask about. A manufacturer who has measured them will simply give you the figures and name the meter. Treat a refusal to answer as more informative than the answer itself would have been.

Electrical and Physical Reality — Check the power draw and the outlet before you buy, not after delivery. Then check the physical fit: floor standing, wall mounted or on an adjustable stand, how much floor it occupies, how far it needs to sit from a wall, and whether it moves easily if the room does double duty. Larger full body panels ship freight rather than parcel, so confirm how it arrives and whether anyone is helping you carry it.

What Comes in the Box — Eye protection, the stand or mount, and the controls. A stand sold separately can add meaningfully to the real price, and a panel you have to prop against furniture is a panel you will use less. If you are buying for home, also check the return window and what it costs you to use it, because the honest test of a panel is a few weeks of your own routine rather than an afternoon of reading specifications.

A Note on Certifications — Marks such as CE and RoHS describe electrical safety and materials compliance. They are worth having and they are not the same thing as a regulatory clearance for a medical purpose. If a seller presents a compliance mark as though it were evidence of a health benefit, that tells you how the rest of their claims are built.

Everything so far applies to any buyer. This section does not. These are the questions that only matter once a panel is generating revenue, and they are the ones most likely to be missed, because essentially all published guidance in this category is written for someone buying for a spare bedroom.

If you are buying for yourself, you can skip to section five. It is worth two minutes anyway, because the warranty point below occasionally catches home buyers as well.

The Expensive One

A large share of consumer panels carry warranties that do not survive commercial use. This is not buried legal boilerplate. One well known brand's warranty states plainly that it applies to consumer use only and does not apply when the product is used in a commercial or institutional setting.

Where a commercial warranty does exist, it is frequently shorter than the residential one. Three years residential against one year commercial on identical hardware is a real and current example. Other brands sell a separate commercial line specifically because the consumer warranty was never written for this.

This is the most expensive item in the guide because of when it surfaces: at the moment a unit fails, which is also the moment it is costing you booked revenue. Get the commercial position in writing before you buy, from every seller on your list, including us. A verbal yes from a salesperson is not a warranty.

Duty Cycle and Heat

A panel used twice a week at home and a panel running back to back sessions from nine until seven are different products inside the same shell. Ask what the maximum recommended continuous run time is, whether the unit is rated for continuous operation, and how heat is managed. Thermal design is most of what separates equipment from consumer goods, and it almost never appears on a spec sheet.

Service, Parts and Downtime

At home a failed panel is an annoyance. In a business it is a cancelled schedule and a refunded client. Settle all of this before purchase, not after:

• Who actually performs warranty service, the manufacturer or a third party
• Where replacement parts ship from, and the realistic turnaround
• Whether individual diode arrays, drivers or boards can be replaced, or whether one failure sends the whole unit back
• Whether an advance replacement or a loaner exists while yours is out

Throughput, and Sizing the Purchase Properly

Work this out before you decide how many panels you need, because it usually changes the answer:

Run that arithmetic before you compare prices. A stronger panel with a shorter session time can be worth considerably more than its price difference across a year of bookings, and that comparison is invisible until you do the math yourself. It is the main reason the cheapest panel is so often not the cheapest decision.

Room, Power and Delivery

Clearance around the unit, ventilation in a small room that is now also generating heat, whether it is floor standing or mounted, and how it moves if the room is shared between services. Confirm the electrical draw per unit and what happens when you add a second and third panel to the same circuit, because retrofitting a treatment room costs many times what planning it does.

Also confirm delivery terms to a commercial address. Freight to a business does not behave like a residential drop off, and a unit that arrives on a pallet at a door with no loading access becomes your problem on the day.

Insurance, and the Claims You Make to Your Own Clients

Two administrative items that are easy to leave until too late. Tell your insurer what equipment you are adding and confirm you are covered for it.

Separately, be deliberate about how you describe the service in your own marketing. The advertising rules that apply to a manufacturer apply to you as well, and inheriting a seller's wording without checking it turns their risk into yours. If a brand hands you marketing copy to use, read it as carefully as you read the warranty.