What Does UV400 Mean on Sunglasses?

Short answer: A UV400 marking means the lens blocks ultraviolet radiation up to 400 nm — that is, full protection from UVA and UVB. Beware: a dark lens does not guarantee UV protection; there must be an explicit UV400 or 100% UV protection marking.

What is UV400?

The UV400 marking means the lens blocks ultraviolet radiation up to 400nm, offering protection from both UVA and UVB.

What does UV400 mean in practice?

Put simply, UV400 means the lenses have a filter that blocks ultraviolet radiation up to a limit of 400 nanometres (nm). That usually corresponds to full UVA and UVB coverage — the two main UV categories linked to eye strain and long-term damage.
Important: the darkness of a lens is not proof of UV protection. In fact, a dark lens without a proper UV filter can be more dangerous, because the eye opens up (the pupil dilates) and lets more ultraviolet radiation through.

Which rays does it cover (UVA / UVB)?

Ultraviolet radiation is divided mainly into UVA and UVB, and UV400 glasses filter both:

• UVA (315–400nm): associated with long-term strain
• UVB (280–315nm): more intense and more damaging radiation
• UVC: does not reach the Earth's surface (absorbed by the atmosphere)

Why is UV400 protection important?

With proper UV protection:

• eye strain is reduced
• comfort in bright sunlight improves
• you avoid the false sense of safety that dark lenses give

Is it enough for the lenses to be dark?

No. A dark tint reduces visible light but does not guarantee UV protection. Always look for a UV400 or 100% UV protection marking.

UV400 vs polarized lenses: what's the difference?

UV400 is about UV protection, while polarized lenses reduce glare on water, tarmac and snow. The two are complementary, not the same thing.

Is UV400 the same as 100% UV protection?

• In most cases, yes (UVA + UVB coverage).
• There should be a clear marking on the packaging or product page.
• Buying from a trusted store reduces the risk of uncertified lenses.

How do I know if a pair is UV400?

1. Check whether there is a UV400 marking
2. See if it is clearly stated on the product page
3. Choose a trusted store

Do you need UV400 in winter too?

Yes. UV radiation is present all year round, especially in the mountains or on snow.

Frequently Asked Questions (FAQ)

What does UV400 mean on sunglasses?

It means protection from UV radiation up to 400nm.

Is UV400 the same as polarized lenses?

No. UV400 = UV protection; polarized = glare reduction.

If the lens is dark, do I have UV protection?

Not necessarily. You need a clear UV400 marking.

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Sources

• European standard: EN ISO 12312-1 (Sunglasses & related eyewear)
• Basic classification of ultraviolet radiation (UVA / UVB / UVC)