Guide · Lamps
Nail lamp wattage and wavelength explained
What a nail lamp's watts and wavelength figures tell you, what they leave out, and what studies found about labels, spectra and price.
Short answer
A nail lamp's wattage is a power figure, and its wavelength is the maker's description of the LEDs. Neither tells you how much light reaches the nail. Measurements of real lamps found that each device had its own spectrum and peak intensity,[1] and that price did not predict UV output.[2] Use wavelength to check a lamp against your gel maker's requirement, and use size and input voltage to check it against your desk and outlet.
What makers publish
| Lamp | Watts | Wavelength | LEDs | Input | Size and weight |
|---|---|---|---|---|---|
| MelodySusie EOS 3 (P-Plus24T) | 48 W | 365-405 nm | 24 | 100-240 V, 50/60 Hz; DC 30 V 1.2 A output | 8.66 x 8.11 x 3.94 in; 248 g[3] |
| SUNUV (all models) | Varies | 365 nm + 405 nm, per SUNUV | Varies | Varies | Varies[4] |
| Kiara Sky Beyond Pro Rechargeable LED Lamp III | Not stated in our source | 400 nm | 30 | Cordless, rechargeable; offered in 120 V (US) | Not stated in our source[5] |
| Kiara Sky Beyond Pro Flash Cure LED Lamp (corded) | 4 W | 400 nm | 2 | AC 100-240 V to a 5 V 1 A micro-USB adapter | 66 x 58 x 47 mm[6] |
All of these are maker statements, not measured spectra or outputs. The Kiara Sky flash-cure figures come from its Australian page; the US version may differ, at least in the plug.[6]
Wattage: what "48 W" does and does not say
A wattage figure on a lamp is a power rating. It does not tell you the irradiance, the amount of light per area that reaches the nail, which also depends on the LEDs, their angle and the distance to the hand.
Read the input and output specs too. MelodySusie lists the EOS 3 at 48 W, but also gives its adapter output as DC 30 V at 1.2 A.[3] Multiplied out, that is 36 W. The 48 W figure may describe something other than what the adapter supplies; the listing does not say. It is one more reason not to choose a lamp by watts.
Wavelength: what "365 + 405 nm" means
Wavelength, in nanometers, describes the color of light the LEDs are built to emit. Gels are formulated to cure under particular wavelengths. MelodySusie explains that UV lamps emit about 350-380 nm, LED lamps about 380-410 nm and dual-band lamps 350-410 nm, and that an LED lamp may cure a UV gel slowly or not at all.[7]
A "365 + 405 nm" lamp is a dual-wavelength lamp: it has diodes aimed at both ranges. A single "400 nm" lamp, like Kiara Sky's Lamp III and corded flash-cure lamp,[5][6] covers a narrower band. Kiara Sky designed its corded flash-cure lamp for its own Gelly Tips system.[6]
Two cautions:
- A stated wavelength is not a measured spectrum. The 2018 Spanish study of 28 nail dryers found each device had its own spectral distribution and peak intensity.[1]
- Labels can be wrong. In the same study, 85% of devices had a visible label, but 23% of those labels contained errors under the EN 60335-1 guideline.[1] That was a labeling-guideline check, not a finding that wavelengths were misstated.
Price is not a proxy either
The 2021 Australian study of eight home devices found that price did not indicate lower UV output or a safer operating temperature.[2] A more expensive lamp is not automatically gentler or stronger.
What to check instead
- Your gel maker's lamp requirement. This decides compatibility; see will any nail lamp cure any gel?.
- The stated wavelength matches that requirement.
- Input voltage and plug for a US or Canadian outlet; see 120 V nail equipment.
- Inside dimensions and size for the hands or feet you will cure.
- Timer presets you will actually use.
Next
Questions
Is a higher-wattage nail lamp better?
Wattage is a power rating, not a measure of light reaching the nail. A 2021 study of eight home devices also found price did not indicate UV output.[2]
What does 365 + 405 nm mean on a nail lamp?
It is a dual-wavelength lamp with diodes aimed at two ranges. SUNUV, for example, states 365 nm + 405 nm for all its lamps. These are the maker's figures, not a measured spectrum.[4]
Are nail lamp labels accurate?
Not always. In a 2018 study of 28 devices in Spanish beauty centers, 23% of the visible labels contained errors under the EN 60335-1 labeling guideline.[1]
Will a 400 nm lamp cure my gel?
Only your gel maker can say. MelodySusie explains that an LED lamp may cure a UV gel slowly or not at all, so check the gel's stated lamp requirement.[7]