The short answer
Most chips do not fail the MOT. On cars aged ten to fourteen, about 1 in 37 first tests recorded windscreen damage as a minor defect (2.7% of 44,980,002 tests in 2021 to 2025), which means the car passed with the damage noted on the certificate. Damage bad enough to fail, recorded as affecting the driver's view, was found on about one test in a thousand at every age.
The line between the two is a size rule in the DVSA inspection manual. In the strip of glass in front of the driver, called zone A, damage larger than 10mm across is a problem. Across the rest of the area the wipers sweep, the limit is 40mm. Damage inside those limits, or outside the swept area altogether, is recorded as minor and the car passes.
What the data shows
Each cell is the share of first tests in that age band that recorded the item. The first two columns are glass damage; the last two are the wiper items that belong to the same visibility family and sit on the same minor-against-major line. Pass after rectification counts as a fail in the national figures, but the items here are counted whenever the tester wrote them down.
| Car age | Windscreen damage, minor (passes) | Windscreen damage affecting view (fails) | Wiper blade defective, minor | Wipers not clearing, major (fails) |
|---|---|---|---|---|
| 3-5 years | 1.6% | 0.1% | 1.2% | 2.3% |
| 6-9 years | 2.0% | under 0.1% | 1.0% | 1.8% |
| 10-14 years | 2.7% | 0.1% | 1.1% | 2.2% |
| 15 years and over | 3.6% | 0.1% | 1.4% | 3.1% |
Minor windscreen damage climbs with age, from 1.6% of tests on young cars to 3.6% on cars of fifteen and over, which fits a windscreen collecting chips over the years and nobody replacing it because it never fails. The fail rate for glass does not climb at all. A separate fail item, the driver's view through the swept area blocked by an obstruction such as a sticker or a sat-nav mount, was recorded on 0.1% of tests from six years upward and under 0.1% on the youngest cars.
Where the line is
The DVSA inspection manual, section 3 sets it out. Zone A is a vertical band 290mm wide, centred on the steering wheel, inside the area the wipers sweep. Damage there larger than 10mm in diameter is what the tester is looking for. In the rest of the swept area the figure is 40mm. The manual is explicit that failure is only justified if the damage significantly affects the driver's view of the road; damage that does not is recorded as a minor defect, and the car passes with it listed. The GOV.UK result page puts it simply: a car fails on dangerous or major problems, and may also come back with a list of minor or advisory problems to monitor or fix.
The same logic runs through the wiper items. A blade that is worn is minor. A blade that is missing, or obviously not clearing the glass, is major and fails. Washers that cannot supply enough fluid for the wipers to clear the screen are major too. That is why the wiper column in the table is the only one of the four that fails more than a sliver of cars.
What to do after a storm, or any stone chip
- Find the chip and measure it. A 10mm circle is about the size of a fingernail; 40mm is about the width of a matchbox. Note whether it sits in the band in front of you or off to the side.
- Deal with it before it spreads. A chip is repairable; a crack that has run across the glass usually is not. Cold nights and a hot demister are what turn one into the other, and both are arriving.
- Check the wipers while you are there. The blade that smeared through the storm is the item in the table most likely to fail you, not the chip.
- Clear the swept area. Dashcams, phone mounts and permits that sit inside the wiped area can be recorded as an obstruction. Move them to the edge.
- Check the weather before you set off. The Met Office warnings page is the source for today's wind and rain.
What this does not mean
These shares describe what testers recorded across the whole fleet. They do not say that a given chip will be recorded as minor; that depends on where it sits and how it looks on the day, and the tester decides. A minor defect still goes on the certificate and a buyer reading the history will see it. Nor is a minor result a reason to leave a chip alone: a repair while it is small is cheaper than a windscreen after it has run.
Frequently asked questions
Usually not. The tester checks for damage larger than 10mm across in the 290mm band in front of the driver and larger than 40mm in the rest of the swept area, and fails the car only if the damage significantly affects the view of the road. Smaller damage is recorded as a minor defect and the car passes.
As a minor defect, on 1.6% of first tests for cars aged three to five rising to 3.6% for cars of fifteen and over, in 2021 to 2025. As a fail, on about one test in a thousand at every age.
It depends on where the crack is and whether it affects the driver's view. A crack that significantly affects the view through the swept area is a major defect and fails. One that does not is a minor defect. The DVSA manual's wording is linked in the article.
It can, if it sits inside the area the wipers sweep and significantly obstructs the driver's view. That item was recorded as a fail on 0.1% of tests on cars aged six and over. Mount it at the edge of the glass.
Sources and method
Shares are tests recording the item divided by all class 4 first tests in the age band (test year minus first-used year), 2021-2025 pooled, across the model groups the item data covers: 33,793,352 tests aged 3-5; 50,103,915 aged 6-9; 44,980,002 aged 10-14; 31,405,150 aged 15 and over. Windscreen damage recorded as minor: 531,590; 1,014,654; 1,225,867; 1,121,176 tests. Windscreen damage affecting the view (fail): 17,436; 23,754; 28,583; 27,103. View obstructed (fail): 11,250; 29,354; 43,417; 39,202. Cells of 0.0% are written 'under 0.1%'. A test can record several items, so columns do not add.
- DVSA anonymised MOT results, class 4 first tests, 2021-2025
- GOV.UK: MOT inspection manual, section 3, visibility
- GOV.UK: MOT test result
- Met Office: UK weather warnings
About these figures. Figures are computed by SortedCars from the DVSA anonymised MOT results dataset (class 4, first tests only, test years 2021-2025), published under the Open Government Licence v3.0. Pass rate = passes divided by first tests, with pass-after-rectification counted as a fail. No figure is shown for any group with fewer than 500 tests. Test class 4 only, first tests only; retests are excluded. Pass rates describe fleets, not individual machines: they reflect how cars were driven, maintained and used as well as how they were built, and beyond recorded mileage none of that is in the data. A well-kept example of a model with a weak average can still pass; a neglected example of a strong one can still fail. Alias spellings of a make are counted under one make name and all trims of a model under one model name, using SortedCars' grouping tables.
This article is general information drawn from published test records. It is not professional, mechanical or legal advice, and an MOT pass or a clean MOT history does not guarantee that a car is roadworthy today. If you are unsure about a car, have it inspected by a qualified mechanic. You can check any vehicle's MOT history free on the official GOV.UK MOT history service.
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