Blue light vs UV light: what is the difference?
By Spektrum Glasses Editorial Team · Published 2026-08-06 · Updated 2026-08-06 · Facts re-checked 2026-08-06 How this page is written and checked: our editorial method · how we verify claimsShort answer
UV and blue light are neighboring bands, not the same thing. UV runs roughly 100-400 nm, is invisible, and carries enough photon energy to break chemical bonds. Blue light runs about 400-500 nm, is visible, and carries far less energy. Ordinary plastic lenses filter almost all UV; filtering the whole blue band requires a visible tint.- UV: about 100-400 nm, invisible. Blue: about 400-500 nm, visible.
- A 400 nm photon carries about 3.10 eV; a 500 nm photon about 2.48 eV.
- Most clear plastic lenses already filter over 99% of UVA and UVB.
- Our clear lens filters 99.99% at 400 nm but only 33.1% at 450 nm.
- Any blue-filtering number is meaningless without the wavelength band.
Where each band sits on the spectrum
Light is usually described by wavelength in nanometers (nm). Shorter wavelength means higher energy per photon. The relationship is fixed and easy to check: photon energy in electronvolts is approximately 1240 divided by the wavelength in nm. Ultraviolet is conventionally split into three sub-bands:- UVC, roughly 100-280 nm. Absorbed by the atmosphere, so it does not reach the ground from sunlight.
- UVB, roughly 280-315 nm.
- UVA, roughly 315-400 nm. This is the great majority of the UV that actually reaches you outdoors.
- Around 400-450 nm, often labeled HEV (high-energy visible) or violet-blue. This is the highest-energy visible light.
- Around 460-480 nm, the region where the melanopsin-based photoreception system in the eye is most sensitive. This is a biological sensitivity peak, not a hazard measure, and the two are frequently confused in marketing copy.
Why UV filtering is nearly universal and blue filtering is not
UV filtering in eyewear is close to a solved problem, and it is cheap. Polycarbonate and most optical-grade plastics absorb UV inherently, and UV absorbers are added on top of that. The result is that a lens can remove essentially the entire UV band without changing its appearance at all, because there is no visible light in that band to remove. A perfectly water-clear lens can be a near-total UV filter. The front of the eye also does a great deal of absorbing on its own. The cornea and the crystalline lens absorb most incoming UV before it reaches the back of the eye, with the lens taking on more of that role with age. Blue is the opposite situation. Every photon you remove between 400 and 500 nm is a photon you would otherwise have seen. Filtering the band strongly and filtering it invisibly are in direct conflict. This is a physical constraint, not an engineering shortfall, and no lens escapes it. A lens that removes most of the blue band will look yellow, amber, orange, or red, and it will shift color perception accordingly. A lens that looks clear is necessarily filtering only the short end of the band hard and tapering off quickly through the rest of it. That is why a single headline percentage for blue is unusable on its own, while a single percentage for UV is broadly meaningful. “Over 99% UV” describes almost the entire band. “Blocks 99% of blue light” describes nothing until you are told which nanometers were measured.What our own lenses measure, band by band
Our clear lens was tested by COLTS Laboratories (report O-SPG111015), an A2LA-accredited lab operating to ISO/IEC 17025, with spectral transmittance measured per ANSI Z80.3. The numbers below show the taper described above in a single lens.
Read the clear-lens column left to right. At 400 nm it is a near-total filter. Fifty nanometers later, at 450 nm, it is filtering a third. Its overall visible transmission is 91.6%, meaning it passes most visible light and looks near-clear. Both facts are true of the same lens at the same time. Our ZENOX clear lens averages about 52% across the blue band with 100% UV, which is the same trade-off at a different setting.
Our tinted lenses sit at the other end. The amber evening lens reaches 97.9% across 400-500 nm. Measured by our lens manufacturer’s optical laboratory in 2026, the orange lens reaches 99.96% across 380-500 nm and the red lens 99.83%. Neither the orange nor the red lens is suitable for driving, because removing that much of the visible spectrum distorts color recognition, including traffic signals.
Where each band actually comes from
Sunlight is the dominant source of both. Outdoors on a clear day, the UV and blue arriving at your eyes exceed anything a screen produces by a wide margin, and it is the only common source of meaningful UVB. Screens are a different case. LED backlights and OLED emitters are electroluminescent devices that produce visible light directly; they do not generate meaningful UV, and the glass and polymer stack in front of them absorbs what little stray shortwave output exists. A phone, monitor, or television is a blue-light source and effectively not a UV source at all. White LEDs, including those in screens and in most modern room lighting, work by using a blue emitter to excite a yellow phosphor. That produces a characteristic spectral peak in the 440-460 nm region. It is a real feature of the spectrum, and it is why LED lighting is discussed differently from incandescent lighting, which had no such peak. It is also why indoor blue exposure is concentrated in a narrow slice of the band rather than spread across it. The practical consequence: if UV is the concern, the relevant behavior is what you wear outdoors. Indoor blue-filtering eyewear does nothing about UV exposure you receive while outside, because you are not wearing it then.What the evidence does and does not support
The UV side is uncontroversial. Filtering UV in eyewear is standard, measurable against published test methods, and reported by accredited labs. That claim is verifiable and boring, which is exactly what makes it trustworthy. The blue side is where the honesty gap opens. The clearest thing to say is that optical filtering and symptom outcomes are two separate questions, and only the first is well settled. On the optics, Leung, Li and Kee (PLOS ONE, 2017) measured commercially available blue-light-filtering lenses and found they reduced the calculated blue-light hazard by roughly 10-24%. That is a calculated optical quantity derived from a weighting function, not a clinical result, and the range is worth sitting with: typical near-clear lenses in that study were not removing most of the band. Our clear lens numbers above are consistent with that picture, front-loaded at the short end and modest by 450 nm. On the biology, the evidence for symptom benefit from blue-filtering eyewear is limited and contested, and we will not represent it as settled. What we can state without qualification is the physical measurement: how much light a given lens passes at a given wavelength, measured by a named accredited lab against a named standard. Everything past that is a separate argument that our lab report does not resolve.How to read a filtering percentage
A short checklist that works on any brand’s page, including ours:- Which band? A percentage with no nanometer range attached is not a specification. “99% at 400 nm” and “99% across 400-500 nm” describe completely different lenses.
- Averaged or at a single point? An average across a wide band and a peak value at one favorable wavelength are both quotable as one number, and they can differ by more than 60 percentage points, as our clear lens shows between 400 nm and 450 nm.
- UV or blue? Over 99% UV is normal for optical plastic and says nothing about the blue band.
- Who measured it, and against what? Look for a named lab, an accreditation such as ISO/IEC 17025, and a test method such as ANSI Z80.3. In-house numbers with no method stated are not comparable to anything.
- What is the visible transmission? A high blue number with a high visible-transmission number is physically suspicious. Filtering visible light and passing visible light are the same measurement.