# Lens tint and VLT guide: filter categories 0–4 explained for sports eyewear

> VLT is the share of visible light a lens lets through. ISO 12312-1 groups sunglass lenses into five filter categories: 0 (80–100% VLT), 1 (43–80%), 2 (18–43%), 3 (8–18%) and 4 (3–8%). Category 3 is the standard choice for bright-sun sports, category 1–2 suits changing light, and category 4 is for glacier or high-altitude use and must never be used for driving.

Published 2026-09-30, updated 2026-10-20. By the Sports Eyewear Factory product team.

## VLT in one sentence

Visible light transmission (VLT), also called luminous transmittance, is the percentage of visible light that passes through the lens. A clear lens is around 90% VLT, a typical dark sports lens is around 10–15%.

## The five filter categories

The international sunglasses standard ISO 12312-1 (published in Europe as EN ISO 12312-1) sorts lenses into five categories by luminous transmittance:

| Category | VLT range | Typical use |
| --- | --- | --- |
| 0 | 80–100% | Clear lenses, night, indoor, shooting |
| 1 | 43–80% | Low light, overcast, forest trails |
| 2 | 18–43% | Medium sun, all-round sport |
| 3 | 8–18% | Bright sun, the most common sport choice |
| 4 | 3–8% | Glacier, high altitude, extreme glare. Not for driving. |

The category must appear on the product or its label when you sell sunglasses in the EU. Ask your supplier for a transmittance test per lens colour, not per model, because a blue mirror and a red mirror on the same frame can fall into different categories.

## Choosing tints by sport

**Smoke and grey (cat. 3).** True colour, even darkening. The safe default for lifestyle sport and running.

**Brown, amber and copper (cat. 2–3).** Boost contrast by filtering blue light. Popular for golf, fishing in shallow water, and trail running.

**Rose and red base (cat. 1–2).** Strong contrast on overcast days and for ball sports. A favourite on our [pickleball sunglasses](https://www.sports-eye-wear-factory.com/products/pickleball-sunglasses/).

**Yellow and orange (cat. 1).** Brighten flat light. Used for night cycling, shooting and fog.

**Clear (cat. 0).** Wind and impact protection at night or indoors. We often ship a clear spare lens with interchangeable cycling and tactical kits.

**Photochromic.** Darkens under UV. A typical sport photochromic lens moves from around category 1 indoors to category 3 in strong sun. Activation slows in cold weather and behind windscreens, which block much of the UV.

## Mirror coatings and VLT

A mirror coating sits on the front of the lens and reflects part of the light before it enters. It lowers VLT and is mainly a styling and glare decision. Blue, ice, red, gold and green revo mirrors are all available on most of our frames. The base tint behind the mirror decides how the world looks to the wearer.

## Practical spec sheet for your order

When you send an inquiry, list each lens as: base tint + mirror + polarized or not + category. For example: *grey base, blue revo mirror, polarized TAC, category 3*. That one line removes most of the back-and-forth during sampling.

Try the tints on our [home page lens tool](https://www.sports-eye-wear-factory.com/#lens-lab), then [ask for a sample set](https://www.sports-eye-wear-factory.com/contact/).

## FAQ

### Which filter category is best for cycling?

Most riders use a category 2 or 3 lens in daylight and a category 0 or 1 clear or yellow lens for dawn, dusk and forest trails. A photochromic lens that moves roughly from category 1 to 3 covers both in one pair.

### Can category 4 lenses be used while driving?

No. ISO 12312-1 requires category 4 lenses to be labelled as not suitable for driving or road use, because they let too little light through.

### Does a darker lens mean better UV protection?

No. Tint darkness and UV protection are separate. A clear lens can block 100% of UV up to 400 nm, while a dark lens without UV absorbers can be harmful because it dilates the pupil.