UK window tint law: what is legal on your car

The short version

UK law only limits the glass in front of the driver's shoulders. For any car first used on or after 1 April 1985, the windscreen must let through at least 75% of light and the front side windows at least 70%. Rear side windows and the rear screen have no limit, so you can go as dark as 5% behind the B-pillar.

Why factory glass changes the maths

Tint percentages describe the film on its own. Your car's glass already blocks some light, typically letting through somewhere between 70% and 90% depending on the manufacturer. Film and glass multiply together, so a 80% film on 88% glass gives roughly 70% overall, while the same film on 80% glass drops to about 64%.

This is why we meter every front window before fitting and recommend 75–80% film for the front sides. You can try combinations yourself in our tint simulator.

What happens if your front windows are too dark

Police and DVSA examiners carry light meters. If your windscreen or front side windows fail, you can be given a prohibition notice that stops you driving the car until the tint is removed, and you may also receive a penalty notice or a court summons. It is also illegal to fit or sell glass that breaks the rules, or to sell a car that already has it.

Chameleon and windscreen films

Colour-shift films are judged on light transmission like any other film. On a windscreen the combined result still has to reach 75%, so the right choice depends on your car's glass. We check this before fitting and will tell you if a particular film would take the car under the limit.

Our approach

We fit rear windows at the shade you choose and front side windows at a road-legal 75–80%. The final reading depends on your glass, and it is the owner's responsibility to keep the car within the rules. For the official wording, see GOV.UK: tinted vehicle windows.