Shade & Temple

What Does UV400 Mean?

UV400 means the lens blocks ultraviolet light up to 400 nanometers, which covers essentially all UVA and UVB. It is the number to insist on, it tells you nothing about how dark the lens is, and it is not the same as polarized. Here is what it covers and how to buy on it.

By Stephen V.Last updated How we pick

How this is funded: we earn a commission if you buy through our links, at no extra cost to you. It never changes which product we recommend, and we’ll tell you when we’d skip one. Full disclosure.

UV400 means the lens blocks ultraviolet light up to 400 nanometers in wavelength. Since the ultraviolet that reaches the ground is UVA at roughly 315 to 400nm and UVB at roughly 280 to 315nm, a lens that cuts off at 400 covers essentially all of it. That is why “UV400” and “100% UV protection” mean the same thing in practice, and why it maps onto the 99 to 100% figure the American Academy of Ophthalmology asks for when it tells you what to look for in sunglasses.

If you only read one more sentence: the number is the floor, it is invisible, and the two things people assume it implies — darkness and polarization — have nothing to do with it.

What the number is actually measuring

Light is described by wavelength, measured in nanometers. Visible light runs from about 400nm at the violet end to about 700nm at the red end. Ultraviolet sits just below the visible range, which is why you cannot see it, and it is divided into three bands: UVA, UVB and UVC. UVC is absorbed by the atmosphere and does not reach you at ground level. UVA and UVB do, and together they occupy roughly 280 to 400nm.

So a filter specified at 400nm is drawing its line at the top edge of the ultraviolet band, immediately below where your vision starts. Everything damaging is on one side of that line and everything you need to see is on the other. There is no such thing as UV500 and there would be no point in it — it would be blocking visible violet light, which is what a tint does.

Why it matters is cumulative rather than dramatic. Public-health bodies including the WHO, the CDC and the FDA tie long-term ultraviolet exposure of the eye to cataract, to growths on the surface of the eye such as pterygium, and to cancers of the eyelid and the surrounding skin; short, intense exposure causes photokeratitis, which is sunburn of the cornea and is the thing skiers call snow blindness. Our guide to cataract risk and the one on snow and reflected light cover both ends of that.

Three things UV400 does not mean

It does not mean dark.The ultraviolet filter is invisible. It can sit in a clear lens, a light tint or a near-black one, and the FDA states the point plainly: how dark a lens looks tells you nothing about its ultraviolet protection. Clear safety glasses are routinely UV400. This is also why the worst purchase in eyewear is a very dark lens with no stated rating — the tint opens your pupil and a weak filter then admits ultraviolet into a wider opening. Our lens category guide covers the numbers that do describe darkness.

It does not mean polarized. Polarization is a separate filter that removes light reflected off flat surfaces, which is a comfort and clarity feature rather than a protective one. A twenty-dollar lens can state UV400 and not be polarized; a premium lens is essentially always both. If you want the glare control, the listing has to say so independently, and do polarized sunglasses block UV is the page for that confusion.

It does not mean mirrored, or coated, or expensive.A mirror coating reflects visible light off the front of the lens and contributes nothing to the ultraviolet figure — see mirrored versus polarized. And price is not the signal either: plenty of budget listings state UV400 while some fashion frames at ten times the money state nothing at all.

Where the protection physically comes from

Two ways, and the difference matters for how long it lasts. In most polycarbonate lenses the ultraviolet absorption is a property of the material itself, so it cannot be scratched off. Oakley makes this explicit about its Plutonite lens material, which it states filters 100% of UVA, UVB and UVC up to 400nm regardless of the tint on top. The alternative is a UV-absorbing treatment applied to the lens, which is how it is usually done on glass and on some prescription lenses, and which deep abrasion can in principle compromise.

In both cases there is no home test that proves a lens still performs — an optician’s photometer is the real answer, and many will check a pair for free. Our page on testing for UV protection is honest about which DIY tests mean something and which are folklore, and do sunglasses expire covers when to replace a pair on scratches alone.

How to buy on the number

Insist on one of three phrasings on the listing: UV400, 100% UV protection, or blocks 99-100% of UVA and UVB. Treat anything vaguer — “UV protection” with no rating, “sun protection”, “dark tinted lens” — as unstated, because it is. Our own registry records this distinction rather than smoothing it over: products whose listings publish a rating show it, and products whose listings do not show “Not published” on their card.

Then add coverage. Ultraviolet arrives from the side and from above as well as straight on, which is why the AAO recommends wraparound or oversized frames, and why a small frame with a perfect lens still leaves your eyelids exposed. After that you are choosing tint, polarization and fit, and nothing you choose there changes the protection.

Three frames that state it, across the price range

One under twenty dollars, one budget pair that is polarized as well, and one premium frame where the protection is a property of the lens material. Every spec below is read from the product’s own listing on the dated visit shown on its card, prices are pulled live, and we have not field-tested any of them.

#1Cheapest listing stating UV400

SOJOS SJ2206 Oversized Polarized Cat Eye

Under fifteen dollars, oversized, and actually polarized — which is the whole point, because most frames at this price sell you a dark lens and stay quiet about UV. The oversized cat-eye front also does something practical: more lens area means more of the skin around your eyes stays covered.

Strengths

  • Polarized with UV400 at an extremely low price
  • Oversized front covers more of the delicate skin around the eyes
  • Low stakes — a beach-bag pair you will not mourn

Trade-offs

  • Budget hinges and coatings; expect a season or two, not a decade
  • Oversized cat-eye is a fashion shape, not a sport one
Lens featurePolarized, UV400, oversized cat-eye
PolarizedYes
Lens tintNot published
Frame materialPolycarbonate (plastic)
UV protectionUV400
Best forEveryday, Beach, Budget, Round & heart faces

Spec note. SOJOS lists the SJ2206 as a polarized oversized cat-eye with UV400 protection.

Specs read from the product listing, on August 10, 2026. “Not published” means the brand does not state that figure.

#2Best UV400 with polarization

Knockaround Premiums (Polarized)

The customizable cheap classic. Knockaround's Premiums come polarized with UV400 protection in a squared shape, and you can mix frame and lens colors endlessly. Genuinely inexpensive, genuinely UV-protective — the pair to buy when you want something specific-looking without spending real money.

Strengths

  • Polarized and UV400 at a low price
  • Endless frame/lens color combinations
  • Squared shape works for round faces and everyday wear

Trade-offs

  • Base plastic build is exactly what you'd expect for the money
  • One size fits most, not all
Lens featurePolarized, UV400, customizable
PolarizedYes
Lens tintVaries by colorway
Frame materialPolycarbonate (plastic)
UV protectionUV400
Best forEveryday, Round faces, Budget

Spec note. Knockaround lists the polarized Premiums with UV400 protection; non-polarized trims of the same frame also exist, so check the SKU.

Specs read from the product listing, on July 18, 2026. “Not published” means the brand does not state that figure.

#3Best UV protection built into the material

Oakley Holbrook OO9102

The frame that bridges sport and street. The squared-off Holbrook is built on Oakley's O Matter frame and Plutonite lens, which blocks 100% of UV on its own. This base SKU isn't polarized — Oakley sells Prizm and polarized versions if you want them.

Strengths

  • Plutonite lens blocks 100% of UV (UVA, UVB and UVC to 400nm)
  • Squared shape flatters round faces and stays out of your lashes
  • Huge range of Prizm and polarized lens upgrades

Trade-offs

  • This base SKU is a non-polarized warm-gray lens
  • Premium price before you add a Prizm or polarized lens
Lens feature100% UV Plutonite lens, squared O Matter frame
PolarizedNo
Lens tintWarm Gray
Frame materialO Matter (nylon)
UV protection100% UV (Plutonite, to 400nm)
Best forEveryday, Golf, Driving, Round & oval faces

Spec note. Oakley's Plutonite lens material filters 100% of UVA, UVB and UVC and harmful blue light up to 400nm regardless of tint.

Specs read from the product listing, on September 5, 2026. “Not published” means the brand does not state that figure.

The point of putting those three side by side is the price spread. On the one spec that is about your eyes rather than your comfort, the sixteen-dollar frame and the premium frame are doing the same job. What the money buys is optics, durability, fit and the polarizing filter — which is a real list, and not a protection list. Are expensive sunglasses worth it works through that properly.

General guidance, not medical or eye-care advice. Shade & Temple is written by an eyewear enthusiast, not an optometrist. The UV and eye-health facts here are attributed to authorities like the American Academy of Ophthalmology, the FDA and the WHO; for an eye exam, a prescription, or a specific concern about your vision, see a qualified eye-care professional.

Frequently asked questions

What does UV400 mean on sunglasses?

It means the lens blocks ultraviolet light with a wavelength up to 400 nanometers. Ultraviolet that reaches the ground is UVA, roughly 315 to 400nm, and UVB, roughly 280 to 315nm, so a lens cutting off at 400nm covers essentially the entire ultraviolet band that matters at the Earth's surface. That is why UV400 is treated as equivalent to the '99 to 100% of UV rays' wording the American Academy of Ophthalmology uses, and why it is the one spec worth insisting on when you buy sunglasses.

Is UV400 the same as 100% UV protection?

In practice yes, and they are two ways of saying the same thing. '100% UV protection' describes how much of the ultraviolet band is blocked; 'UV400' describes the wavelength the lens cuts off at, which happens to be the top of that band. A lens stating either one clears the AAO's guidance. What matters more than which phrase a listing uses is that it states one of them at all — a dark lens with no ultraviolet claim anywhere on the listing is the thing to walk away from.

Does UV400 mean polarized?

No, and this is the most expensive misunderstanding in sunglasses. UV400 is about invisible radiation that damages the eye over years. Polarization is about visible light reflected off flat surfaces, which is uncomfortable right now. They are separate layers, they are sold separately, and plenty of lenses have one without the other — a cheap UV400 pair that is not polarized is common, and a premium polarized pair is always also UV-protective. If you want both, the listing has to state both.

Does UV400 mean the lens is dark?

Not at all, and darkness is not protection. The ultraviolet filter is invisible: it can be applied to a clear lens, a light tint or a near-black one, and you cannot see or feel the difference. The FDA makes this point directly — how dark a lens looks tells you nothing about whether it blocks ultraviolet. Clear safety glasses are routinely UV400. Meanwhile a very dark lens with a weak filter is actively worse than no sunglasses at all, because the tint opens your pupil while letting ultraviolet into the wider opening.

What does UV400 CE mean?

They are two separate marks that often appear together on cheap listings. UV400 is the ultraviolet cut-off. CE is a European conformity marking, which for sunglasses relates to the EN ISO standard covering filter category, optical quality and ultraviolet performance — so a genuine CE mark implies the product was declared to meet that standard. The practical caveat is that both marks are printed by the seller, and neither is a test you can see the results of. For a pair you already own, our UV testing guide covers what you can and cannot verify yourself.

Is UV400 enough for driving, snow or water?

It is enough for the ultraviolet part, everywhere. What changes between environments is the visible light, not the ultraviolet filter. On snow and water you are getting a second dose of reflected light from below, so you want a darker tint and ideally a polarizing filter and side coverage — but not a higher UV number, because 400nm already covers the band. The same goes for altitude. UV400 is a floor you should never go below and a ceiling there is no point going above.

Can a UV400 lens stop working?

The filter itself does not wear out in a lens where ultraviolet protection is built into the material, which is how most polycarbonate lenses work. Where the protection is a coating, deep scratches and heavy abrasion can compromise it, and nobody can tell you by eye whether a given scratched lens still blocks what it claimed. Scratches are a good reason to replace a pair regardless, because a scratched lens scatters light exactly where you are trying to see through it. Our guide on whether sunglasses expire covers the sensible replacement rules.

Sources

Keep reading