Last updated: October 2026
Polarized and UV400 are two different features. UV400 lenses block ultraviolet light up to 400 nanometres, which covers UVA and UVB rays, so they protect your eyes. Polarized lenses filter reflected glare from flat surfaces such as water, roads, and snow, so they improve comfort and clarity. Polarization alone does not guarantee UV protection. Good sunglasses have both.
What does UV400 mean?
UV400 means the lens blocks light with wavelengths up to 400 nanometres. That range includes both UVA and UVB, the ultraviolet rays that reach the ground and that eye-care organisations link to long-term eye damage. A lens labelled UV400 or "100% UV protection" offers full UV blocking.
UV protection is invisible. It does not depend on how dark the lens is. A dark lens without UV protection can be worse than no sunglasses, because your pupils widen behind it and let more UV in.
What does polarized mean?
Sunlight scatters in all directions, but when it bounces off a flat surface it becomes concentrated in one plane, mostly horizontal. That is glare. A polarized lens contains a filter that blocks this horizontal light and lets the rest through. The result is less squinting, better contrast, and the ability to see through the surface of water instead of only its reflection.
Polarized vs UV400: side-by-side
|
Request |
UV400 |
Polarized |
|---|---|---|
|
What it blocks |
Ultraviolet light up to 400 nm (UVA and UVB) |
Reflected glare from flat surfaces |
|
Main benefit |
Eye health protection |
Visual comfort and clarity |
|
Can you see the effect? |
No |
Yes, immediately |
|
Depends on lens darkness? |
No |
No |
|
Needed every time outdoors? |
Yes |
Depends on the activity |
|
Includes the other feature? |
Not polarized by default |
Not UV-protective by default; check the label |
Do you need both?
For most outdoor use, yes. UV400 is the baseline that every pair of sunglasses should meet. Polarization is the upgrade that makes the biggest visible difference in bright, reflective conditions.
|
Activity |
UV400 |
Polarized |
|---|---|---|
|
Driving in daylight |
Essential |
Strongly recommended: cuts glare from wet roads and windshields |
|
Fishing and boating |
Essential |
Strongly recommended: lets you see below the water surface |
|
Beach, running, cycling, hiking |
Essential |
Recommended |
|
Skiing on icy slopes |
Essential |
Optional: some skiers prefer to see glare from ice patches |
|
Reading phone or LCD screens a lot |
Essential |
Optional: screens can look dim at some angles |
How can you tell if sunglasses are polarized?
Look at a phone or laptop screen through the lenses and slowly rotate the glasses 90 degrees. If the screen darkens or goes black at some angle, the lenses are polarized. You cannot test UV protection at home in the same way. Rely on the label, or ask an optician to check with a UV meter.
Are polarized lenses bad for anything?
They can make some LCD screens, such as car displays, ATMs, and phones, look dim or patchy at certain angles. Pilots are usually advised against them for this reason. For everyday driving and outdoor sport, the benefit outweighs this for most people.
BEX sunglasses at Sigonna are sport frames built around polarized lenses. Check the lens details on each product page for polarization and UV rating.
FAQ
Is polarized better than UV400? Neither is better, because they do different jobs. UV400 protects your eyes. Polarized reduces glare. The best choice is a lens with both.
Are all polarized sunglasses UV400? No. Most quality polarized sunglasses include UV400 protection, but polarization itself does not block UV. Always check for a UV400 or 100% UV label.
Do polarized sunglasses protect your eyes more? They make vision more comfortable and reduce eye strain from glare. Protection from ultraviolet damage comes from the UV filter, not the polarizing filter.
Are polarized sunglasses worth it for driving? Yes for daytime driving. They reduce glare from the road, other cars, and low sun. They are not suitable for night driving, because any tinted lens reduces the light reaching your eyes.
Do darker lenses block more UV? No. Lens tint controls visible brightness only. A clear lens can block 100% of UV, and a very dark lens can block none.
Do polarized sunglasses work on cloudy days? Yes. UV passes through cloud, and glare from wet roads and water is often strong on overcast days.
