Sunglasses Lens Categories 0 to 4: How to Choose the Right Tint
Sunrise Ibiza
There is a particular moment on an Ibiza terrace, somewhere around three in the afternoon, when the light stops being pleasant and turns openly hostile. Whitewashed walls throw it straight back at you, the sea glitters, and you find yourself squinting even with your sunglasses on. At that point the question is no longer whether your lenses look good. It is whether they are dark enough for the light you are actually standing in.
That answer already exists, stamped somewhere on the frame as a single digit between 0 and 4: the lens category. It is probably the most useful piece of information on the whole pair, and almost certainly the most overlooked. Here is what it really means, and how to use it.
What the number actually tells you
A lens category measures exactly one thing: how much visible light the lens lets through to your eye. This is called luminous transmittance, and it is expressed as a percentage. A lens transmitting 90% of the light is close to clear; one transmitting 10% is properly dark.
The scale is set by the European standard EN ISO 12312-1, which defines five levels from 0 to 4. The higher the number, the darker the lens. That is all there is to it, and that simplicity is precisely why the category is such a reliable reference point: it does not depend on the lens colour, the brand or the price.
Category and UV protection are not the same thing
This is the single most common misunderstanding, so let us clear it up straight away. A very dark lens is not automatically a lens that blocks ultraviolet light. Tint governs visual comfort; UV filtering governs the health of your eyes. They are two separate treatments.
Worse still, a heavily tinted pair with poor filtering is more harmful than wearing nothing at all, because the darkness makes your pupils dilate and lets more UV in. The only marking that guarantees full filtering is the UV400 standard, which blocks radiation up to 400 nanometres. Always check both: a suitable category and UV400 protection.
The five categories, one by one
Category 0: 80% to 100% light transmission
Clear or barely tinted lenses. They filter almost none of the brightness and belong more to the world of style than of sun protection. You will find them on fashion frames worn indoors, or on lightly tinted lenses. Keep them for overcast skies and late evenings.
Category 1: 43% to 80%
A light tint, comfortable in low to moderate light. This is the category for grey days, autumn walks through the city, or the last hour before dusk. It adds genuine comfort without darkening your view, but full summer sun will overwhelm it quickly.
Category 2: 18% to 43%
The middle ground. A medium tint suited to average sunlight: a bright city, a shaded terrace, a clear spring day. Plenty of gradient lenses sit in this range, denser at the top and lighter towards the bottom, which makes them an elegant choice if you are constantly moving between indoors and out.
Category 3: 8% to 18%
This is the sunshine category, the real one. Mediterranean summers, beaches, boat decks and the white streets of the Balearics. The vast majority of sunglasses sold for summer wear fall here, simply because it matches the conditions in which people actually reach for sunglasses.
If you are choosing a pair for a trip to Ibiza, a festival or a day out on the water, this is where to look. It cuts glare properly without turning the afternoon into artificial dusk.
Category 4: 3% to 8%
Very dark lenses, built for extreme conditions: high mountains, glaciers, deserts, fierce glare off snow. They are not everyday wear.
One important point: category 4 is not permitted for driving in the EU, day or night, because it dims the field of view too much for safe reaction times. The UK applies the same standard. If you will be behind the wheel, stay at category 3 or below — we go into the detail in our guide to sunglasses for driving.
Which category for which situation?
| Category | Light transmitted | Best for | Driving |
|---|---|---|---|
| 0 | 80–100% | Indoors, overcast skies, evening | Day and night |
| 1 | 43–80% | Grey weather, low light | Day and night |
| 2 | 18–43% | Average brightness, city, shoulder season | Daytime only |
| 3 | 8–18% | Full sun, beach, sea, mountains | Daytime only |
| 4 | 3–8% | Glaciers, high altitude, desert | Not permitted |
How to choose the right category in four steps
1. Start from where you actually wear them
Not the exception, the everyday. If your sunglasses mostly come out in summer, by the water or in a very bright city, aim for category 3. If you wear them chiefly around town in a temperate climate, category 2 is plenty and stays more comfortable when you step into the shade.
2. Factor in your own sensitivity
Light eyes are statistically more prone to glare, as are tired eyes or eyes that have recently had surgery. Under identical conditions, someone with blue eyes will be happier in category 3 where others are perfectly content in category 2. Trust your comfort: if you are still squinting, your tint is too light.
3. Check they work for driving
If the same pair has to serve you at the wheel, rule out category 4 immediately and make sure the lenses do not distort traffic light colours. Grey and brown tints are the most neutral here.
4. Check the markings before you buy
A serious pair states its category and its CE conformity. If nothing appears on the temple, on the label or in the product description, assume nothing is guaranteed and walk away.
Category, colour and polarisation are three different things
Three characteristics share the same lens, and each answers a different need.
Category sets how much light is filtered out. Colour changes the rendering and contrast: brown warms things up and lifts detail, grey keeps colours faithful, yellow brightens hazy conditions, blue or pink are chiefly a style decision. Two category 3 lenses can therefore feel completely different to wear depending on their tint — which is the subject of our guide to coloured lenses.
Polarisation, finally, is a separate technology altogether: it removes horizontal reflections off water, roads and sand. A lens can be polarised at category 2 or category 3, and a non-polarised category 3 lens still protects you perfectly well.
Where to find the category on your sunglasses
In most cases it is printed inside the left temple, as a CE marking followed by a digit, or spelled out as "sun filter category 3". It may also appear on the original label, on the leaflet supplied with the case, or in the technical specifications of an online product page.
If you are buying online, that information should be available before you pay. A shop that stays vague about the protection its lenses offer is rarely a good address.
How Sunrise Ibiza approaches it
Every pair in the shop is built for the light the brand is named after: the light of an island where the sun makes no concessions. Our lenses are polycarbonate with UV400 filtering covering UVA and UVB up to 400 nanometres, and they meet CE marking requirements. The technical details for each model are listed on its product page.
The styles take different routes. The ICON collection goes for bold tints and clean lines — think AMNESIA with its opaque smoked lenses, made as much for full sun as for the small hours. The VINTAGE collection leans into tortoiseshell frames and retro gradients. SIGNATURE, meanwhile, explores less obvious pairings, such as SANT ANTONI and its blue-to-beige gradient, lifted more or less directly from the colours of sunset over the bay.
For something more versatile, gradient lenses — USHUAÏA and its crystal frame being the clearest example — vary in density from top to bottom, which helps when you are forever moving between terrace and interior. Everything sits together in the Sunglasses collection.
After that comes the question of style, which has nothing to do with technical specifications and everything to do with enjoying what you wear: our guides on choosing a frame and on Ibiza sunglasses style pick up the thread from there. And if you want to test your pair in the best possible conditions, our sunset spots around the island remain the ideal proving ground.
Frequently asked questions
Which lens category should I choose for summer?
Category 3 is the reference for summer in southern Europe: beaches, seafronts, terraces, festivals. It transmits between 8% and 18% of light, which cuts glare without darkening your view excessively.
Is category 4 really banned for driving?
Yes. In the EU, category 4 lenses are not permitted for driving, day or night, because they reduce the amount of light reaching your eyes too far. They are reserved for high mountains and environments with extreme glare.
Does category 3 automatically mean UV protection?
No. The category describes only the tint of the lens, not its ultraviolet filtering. A category 3 lens without UV treatment lets harmful rays through while your pupils are dilated. Always look for UV400 alongside the category.
Can I wear category 3 lenses indoors?
Nothing stops you, but comfort suffers: your view goes dark and contrast drops away. For mixed indoor and outdoor use, a gradient lens or category 2 will be considerably more pleasant.
Do gradient lenses have a category of their own?
They are classified on their average transmittance and usually land in category 2 or 3. Their appeal lies in the varying density: darker at the top to cut the light from the sky, lighter at the bottom so you can still see clearly downwards.
How do I know whether my current sunglasses comply?
Look inside the left temple: the CE marking and category number are usually printed there. If there is no indication at all, on the frame or on the packaging, it is wise to assume the protection is not guaranteed.
