How to Choose Polarized Sunglasses: UV400, Lens Category and Fit
Polarized sunglasses are one of the most common accessory purchases, and also one of the easiest to get wrong. Two pairs can look identical online yet differ in how much UV they block, how dark the lenses are, and whether they suit driving. Price is not a reliable guide either: a modest pair with the right labels can protect your eyes as well as a designer one. This guide covers what the terms on a product page mean and what to check before you buy.
UV protection comes first
Darkness and polarization are about comfort; UV protection is about eye health. Look for one of these statements on the product page or the label:
- UV400 or 100% UV protection, meaning the lenses block ultraviolet light up to 400 nanometers, which covers both UVA and UVB.
- A standard reference, such as ANSI Z80.3 in the US or ISO 12312-1 (the basis of CE and UKCA marking in Europe and the UK).
A dark lens without UV filtering can be worse than no sunglasses at all, because your pupils open wider behind the tint. If a listing does not mention UV protection, assume it is not there.
What polarization does, and when it does not help
Polarized lenses cut horizontal glare: the bright reflections off water, wet roads, snow and car hoods. That makes them popular for driving, fishing, boating and beach days. A few trade-offs are worth knowing:
- They can make LCD screens, such as phone displays, car dashboards and fuel pump readouts, look dim or patchy at certain angles.
- Pilots and some skiers prefer non-polarized lenses, because glare off ice or instruments can carry useful information.
- Polarization is not the same as UV protection. A polarized lens should also state UV400 or 100% UV.
Understand lens categories
Many sunglasses list a filter category from 0 to 4, which describes how much visible light gets through:
- Category 0–1: clear to lightly tinted, for fashion or overcast days.
- Category 2: medium tint for everyday sun.
- Category 3: dark tint for bright sun, the most common choice for general outdoor use.
- Category 4: very dark, for high mountains or glaciers; not suitable for driving.
Mirrored coatings reflect extra light and add style, but they scratch more visibly than plain lenses, so a hard case matters more.
Lens color and material
Gray lenses keep colors most natural. Brown or amber add contrast and are popular for driving and golf. Rose, yellow and blue tints are mostly a style choice. Polycarbonate lenses are light and impact-resistant; glass is more scratch-resistant but heavier and can shatter. Ask whether the lenses have a scratch-resistant coating if the material is not listed.
Getting the fit right
Most frames have three numbers printed inside one arm, such as 54-18-140: lens width, bridge width and temple length in millimeters. If you own a pair that fits well, compare those numbers with the new frame. Good sunglasses should:
- Sit level without pinching at the temples or sliding down your nose
- Cover your eyes fully, including at the sides if you spend long hours outdoors
- Keep your eyelashes off the lenses
Check the extras and the paperwork
A hard case and a microfiber cloth extend the life of any pair. Before ordering online, read the return window and whether it covers worn items, the warranty on hinges and frames, and, if you are buying from another country, the shipping cost and possible import duties.
For an example of how a small brand presents these specs, see our True Vision review.
A quick checklist
- UV400 or 100% UV protection stated clearly
- Polarized if you drive or spend time near water or snow
- Category 2–3 for everyday sun; never category 4 for driving
- Lens color that suits your main activity
- Frame measurements close to a pair that already fits you
- Hard case included, plus a fair return window and warranty