SunticHow to Choose Sunglasses That Actually Block UV
A pair of sunglasses can look identical to another and offer very different UV protection, because the two things people usually judge by, how dark the lenses are and whether they're polarized, don't actually tell you much. Here's what to look for instead, and why the wrong pair can do more harm than none at all.
What does UV400 actually mean?
UV400 means the lenses block light with wavelengths up to 400 nanometres, which covers essentially all UVA and UVB radiation. It's the benchmark to look for, alongside labelling like '100% UV protection'. Cheap sunglasses can carry this rating just as reliably as expensive designer ones. Price is not a reliable signal of UV protection; the label is.
Does a darker lens mean more protection?
No, and this is the single most common mix-up. Lens tint controls how much visible light gets through, which affects glare and comfort, not how much UV is filtered. A very dark lens with no UV coating can actually be riskier than a lighter, properly UV-rated one, because darker lenses make your pupils open wider to let in more light, and if UV isn't being filtered, more of it reaches your eye. Always check for a stated UV rating rather than judging by how dark or expensive a pair looks.
Isn't polarized the same as UV-protective?
No, they solve different problems. Polarized lenses use a special filter to cut glare from flat, reflective surfaces like water, snow or a wet road, which is genuinely useful for driving, fishing or the beach. But polarizing is unrelated to UV filtering: a polarized lens still needs its own separate UV coating or rating to actually block UV. Look for both a polarized label and a stated UV rating if you want each benefit; one doesn't guarantee the other.
What else actually helps?
- Wraparound or close-fitting frames block more UV reaching the eye from the sides, not just straight ahead.
- Bigger lenses cover more of the delicate skin around the eyes, which is thin and prone to sun damage too.
- Reflection adds up: water, snow, sand and pale pavement all bounce extra UV toward your eyes, so protection matters even on an overcast beach day. See UV reflection from water, snow and sand.
- Kids and people with light-coloured eyes are generally more sensitive to UV and glare, so a properly rated pair matters just as much, if not more.
Why protect your eyes at all?
UV exposure to the eyes over time is linked to conditions like cataracts and other long-term eye damage. We cover the detail in UV and your eyes. Pairing properly rated sunglasses with the same habits you'd use for your skin, shade around midday and awareness of the live UV index, gives your eyes the same layered protection Suntic helps you apply to the rest of your skin.
Frequently asked questions
What does UV400 mean on sunglasses?
It means the lenses block light up to 400 nanometres, covering essentially all UVA and UVB. Look for this or a '100% UV protection' label rather than judging by lens darkness or price.
Do polarized sunglasses block UV?
Not automatically. Polarizing reduces glare from reflective surfaces, which is a different feature from UV filtering. A polarized lens needs its own separate UV rating to actually block UV.
Does a darker lens mean better UV protection?
No. Tint affects how much visible light gets through, not UV filtering. Unrated dark lenses can be riskier than lighter, properly UV-rated ones because your pupils dilate more behind them.
Do expensive sunglasses block more UV than cheap ones?
Not necessarily. Many inexpensive sunglasses carry a genuine UV400 or 100% UV protection rating. Check the label rather than the price tag.
