Is Driving With a Cracked Windscreen Legal? UK Law Explained

Written by the MyCarGlass team. Reviewed by Manish Patel, founder, and Robert Webster, windscreen expert — fitting glass since 1995. Last updated 20 June 2026.

It’s one of the most-searched questions UK drivers ask about their cars, and the answer is genuinely important: driving with a cracked windscreen can be illegal, can fail your MOT, and can land you with a fine and penalty points — but it depends heavily on where the damage is and how big it is. This guide sets out what the law actually says, how the MOT assesses it, and the penalties for getting it wrong.

Is it actually illegal to drive with a cracked windscreen?

It can be. There’s no single law that says “a cracked windscreen is illegal” in all cases. Instead, two things combine:

First, the law requires you to have a full view of the road ahead and that the glass is maintained so it does not obscure your vision. This comes from Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986.

Second, it’s an offence to use a vehicle in a dangerous condition — under Regulation 100 of the same regulations and Section 40A of the Road Traffic Act 1988 — where a defect (including damaged glass) creates a danger of injury.

So a crack that obscures your view or makes the screen insecure can make the car illegal to drive, while a tiny chip in the corner generally won’t. The deciding factors are size and location, which is exactly what the MOT zones measure.

What are the MOT windscreen damage rules?

The MOT divides the windscreen into zones based on the driver’s view, and applies a stricter limit directly in front of the driver:

Zone A is a vertical band 290 mm wide, centred on the steering wheel, within the wiper-swept area (this is 350 mm wide on vehicles over 3.5 tonnes). In Zone A, a single area of damage must be contained within a 10 mm circle.

Zone B is the rest of the swept area. There, a single area of damage must be contained within a 40 mm circle.

In addition, a crack that passes through the swept area and reaches the edge at two points is treated as rendering the windscreen insecure — an automatic problem regardless of the zone limits. The overarching MOT test is whether the damage significantly affects the driver’s view of the road, so the size thresholds aren’t applied in complete isolation.

So a 12 mm chip directly ahead of the driver can fail the MOT, while a 30 mm chip out near the passenger side may pass. Size alone isn’t the test — size in a given zone is.

“Drivers fixate on how big the crack is. The MOT cares far more about where it is. Ten millimetres in front of your eyes is a fail; the same damage in the corner often isn’t. If it’s anywhere in the band swept by your wiper in front of the wheel, treat it as urgent.” — Robert Webster, windscreen expert, MyCarGlass

What’s the penalty for driving with a defective windscreen?

If a windscreen is damaged enough to obscure vision or make the vehicle dangerous, you can be penalised for using a vehicle in a dangerous/defective condition. Commonly cited consequences are:

• a fixed penalty of £100 and 3 penalty points on your licence — the offence is recorded under endorsement code CU20 (“using a vehicle with parts or accessories in a dangerous condition”), which carries 3 points and stays on your licence for 4 years; and
• if it goes to court instead, a considerably higher fine of up to £2,500 and discretionary disqualification, with penalty points.

A police officer or DVSA examiner can also issue a prohibition notice that stops you driving the vehicle until the windscreen is fixed.

It’s also worth knowing that driving with a windscreen defect could affect an insurance claim if you were involved in an incident while the car was in an unroadworthy state — another reason not to let damage sit.

What about sat-navs, dashcams and stickers in the windscreen?

It isn’t only damage that’s judged by the zones — anything that obstructs the driver’s view is too, and it’s governed by the same Zone A and Zone B rule. An object or sticker in Zone A (the 290 mm band in front of the driver) must stay within the 10 mm limit, and in Zone B within 40 mm. In practice that means:

A sat-nav or phone mount should be sited low in the corner of the windscreen, clear of Zone A, so it doesn’t intrude into your forward view. A dashcam is best mounted behind the rear-view mirror, where it sees the road without sitting in your eyeline, and should not protrude more than 40 mm into the wiper-swept area. Stickers — tax-type reminders, parking permits, car-park tickets — belong outside the swept area or tucked behind the mirror, not in Zone A. Loosely hung air fresheners or fluffy dice swinging in your view can also count as an obstruction.

The consequences mirror those for damage: an obstruction in your view can mean an MOT failure, and at the roadside a £100 fixed penalty and 3 points for not having a clear view of the road. Badly placed dashcam footage can even be ruled inadmissible. The simple test is the same one the MOT uses: nothing of any size should significantly block the driver’s view of the road ahead.

Does a cracked windscreen automatically fail the MOT?

Not automatically — it depends on the zones above. Damage outside the limits for its zone, or a crack making the screen insecure, will fail. Damage within the limits, and not significantly affecting the driver’s view, can pass. But “passes the MOT today” isn’t the same as “safe and legal to keep driving” — cracks spread, and a borderline pass can become a fail (and a dangerous-condition offence) after one cold night.

What should I do if my windscreen cracks?

Act quickly, and let the size and location guide urgency:

If the damage is small, shallow and away from your line of sight, it may be repairable — book a windscreen repair promptly before it spreads. If it’s in Zone A / your line of sight, large, long, at the edge, or reaching two edge points, you likely need a replacement, and you should treat driving as a risk until it’s done. For a screen that’s shattered, badly cracked or unsafe right now, use our emergency windscreen service.

Whatever you do, don’t ignore it. The cheapest, easiest, most legal outcome is almost always the early one. Our full decision framework on sizes and zones is in Windscreen chips and cracks: repair or replace?

“If the crack’s in your eyeline, my advice is simple: don’t drive it any further than you have to. It’s a safety issue first and a legal one second. We run an emergency service for exactly this — better a quick call than a prohibition notice or worse on a wet motorway.” — Manish Patel, founder, MyCarGlass

Quick answers

Can I drive with a chip in my windscreen? Usually yes if it’s small and outside your line of sight — but get it repaired quickly before it spreads.

Can I drive with a crack in front of the driver? Treat it as no — damage over 10 mm in Zone A can be illegal, dangerous and an MOT failure.

Will a cracked windscreen fail the MOT? It will if the damage exceeds the limit for its zone (10 mm in Zone A, 40 mm in Zone B) or makes the screen insecure.

What’s the fine? £100 and 3 points (endorsement code CU20) by fixed penalty — and considerably more, up to £2,500 and possible disqualification, if it goes to court.

Can I drive it to a garage to get it fixed? There’s no special legal exemption for driving to a repair. If the screen is dangerous or obscures your view, driving it — even to a garage — is an offence, so book a mobile repair or our emergency service to come to you rather than risk it. If the damage is minor and outside your line of sight, drive straight there and don’t delay.

Is a cracked rear windscreen or side window illegal? The view-to-front rules apply to the front glass, so a cracked rear or side window isn’t judged the same way — but it can still make the car illegal if the glass is insecure or likely to shatter, which is a dangerous-condition issue, and a shattered side or rear window leaves you exposed to theft and the elements. Get it replaced promptly.

The bottom line

Whether driving with a cracked windscreen is legal comes down to size and location: small damage outside your line of sight is usually fine to drive to a repair; damage in your forward view (Zone A, over 10 mm), large damage in Zone B (over 40 mm), edge cracks, or an insecure screen can make the car illegal, dangerous and an MOT failure — with fines, points and a possible prohibition. The safe move is always to fix it early.

We’re family-run, fitting glass since 1995 — over 30 years — with in-house fitters, a 7-year guarantee, and a 5.0 rating on the road to 1,000+ 5-star reviews. Phones are manned until 7pm with an AI assistant after hours, and we run an emergency service for unsafe screens. Get help now or call 020 8909 2300.

This article summarises UK government guidance for general information and is not legal advice. Figures are accurate at the time of writing; always check current GOV.UK guidance and your vehicle’s specifics.

Sources

• GOV.UK — View to the front and windscreen obscuration
• GOV.UK — MOT inspection manual: visibility
• Legislation.gov.uk — Road Vehicles (Construction and Use) Regulations 1986