Windscreen MOT Rules UK
What size chip or crack will fail your MOT? The exact size limits, zone definitions, and what you can do before your test date.
Quick Answer
A chip larger than 10mm in Zone A (directly in front of the driver) will fail your MOT. A chip larger than 40mm in Zone B (rest of the swept area) will also fail. Damage outside the swept area is not tested.
Zone A and Zone B Explained
The windscreen is divided into zones for MOT testing purposes. Only the area swept by the wipers is tested. Damage outside the swept area does not affect your MOT result.
Zone A
A 290mm-wide vertical strip centred on the steering wheel, within the swept area of the wipers. This is the driver's primary line of sight.
Max damage: 10mm
Zone B
The rest of the area swept by the wipers, excluding Zone A. This includes the passenger side and the upper/lower edges of the swept area.
Max damage: 40mm
Outside Swept Area
Anything outside the area reached by the wipers. This includes the very edges and the area above the wiper arc.
Not tested
MOT Size Limits
| Zone | Maximum Damage Size | Result |
|---|---|---|
| Zone A | 10mm | Any damage over 10mm fails |
| Zone B | 40mm | Any damage over 40mm fails |
| Outside swept area | Not tested | Does not cause MOT failure |
Repair Before Your MOT
A properly repaired chip can pass an MOT. The resin fills the damage and restores structural integrity. A good repair leaves minimal distortion and will not trigger a failure.
Get the repair done well before your test date. A chip repair costs £40 to £70 (or free through insurance) and takes 30 minutes. That is far cheaper and simpler than failing your MOT, rebooking the test, and paying for a rushed replacement.
Free retest. If your car does fail on a windscreen defect, you are entitled to a free partial retest at the same test centre if the repair or replacement is completed within 10 working days.
Driving with a Cracked Windscreen
You do not need to wait for your MOT to be at risk
The police can issue a fixed penalty notice if your windscreen damage impairs your vision, regardless of when your MOT is due. The offence falls under the Road Vehicles (Construction and Use) Regulations 1986, which requires that windscreens be maintained in a condition that does not obstruct the driver's view.
A fixed penalty for this offence is typically three penalty points and a fine. In serious cases (such as driving with a severely cracked windscreen in rain), it could be treated as driving without due care and attention.
The practical advice: if you have a crack in your line of sight, get it fixed immediately. Do not wait for your MOT.
Frequently Asked Questions
Can a repaired chip pass an MOT?
Yes. A good-quality resin repair will be nearly invisible and will not cause an MOT failure. Get chips repaired well before your test date.
Is a crack at the edge of the windscreen an MOT fail?
Only if it falls within the swept area of the wipers. If the crack is within the swept area and exceeds the zone limits (10mm in Zone A, 40mm in Zone B), it will fail. Damage outside the swept area is not tested.
Can I get a free retest if I fix the windscreen?
Yes. If your car fails on a windscreen defect and is repaired within 10 working days, you are entitled to a free partial retest at the same test centre.