It depends on the size and location of the crack. Damage up to 10mm in the driver's direct line of sight (Zone A) is acceptable, as is damage up to 40mm elsewhere. Anything larger, or anything that obscures the view, will likely be a fail.
It’s one of the most common questions I hear from anxious drivers dropping their car off: "I've got a chip in my windscreen, will it fail its MOT?" It's a fair question. A stone flicking up on the motorway can happen to anyone, and the thought of a costly windscreen replacement on top of any other potential repair work is enough to cause a bit of stress. First, let's get one thing straight: not every crack or chip is an automatic MOT failure. Far from it. The rules are quite specific, and they're designed with a single purpose in mind: to ensure the driver has a clear, unobstructed view of the road ahead. It's all about safety, not about catching you out for minor imperfections. Over my 20+ years as an MOT tester, I've seen everything from tiny starburst chips to cracks that stretch from one side of the glass to the other. In this guide, I'll walk you through the official DVSA rules, explain how we testers actually apply them in the real world, and give you some honest, practical advice on what to do if your windscreen is less than perfect. My goal is to demystify the process so you can approach your next MOT with confidence.
The official UK MOT rule
Right then, let's get down to brass tacks. The rules we follow come directly from the DVSA's 'MOT inspection manual for private passenger and light commercial vehicles'. The bit we're interested in is Section 3, which covers 'View to the front'. Specifically, item 3.2: 'Windscreen'. The manual is very precise and splits the windscreen into two distinct areas. This is the most important thing to get your head around: * **Zone A:** This is a 290mm wide vertical strip, centred on the steering wheel. It's essentially the driver's direct line of sight, the critical area you look through for the maj
How testers actually assess this
Reading the manual is one thing, but what actually happens when your car is in the test bay? Let me walk you through my process for checking a windscreen. It's a physical, hands-on check, not just a quick glance from outside the car. First, I sit in the driver's seat, exactly where you would sit. This is vital, because I need to see the world from your perspective. I'll look for any obvious chips, cracks, or cloudy areas. I'm especially focused on that critical Zone A, directly in front of my eyes. If I spot anything, my next step is to measure it. We have official DVSA-approved tools, which a
Common scenarios — pass, advisory or fail?
Theory is all well and good, but let's look at some real-world examples that I see almost every week. This should give you a much clearer idea of where your own windscreen might stand. * **Scenario 1: The tiny stone chip.** A lorry kicks up a stone on the A1 and leaves a small, 6mm 'bullseye' chip right in the driver's line of sight (Zone A). Is it a fail? **No, this is a Pass.** The damage is well within the 10mm limit for Zone A. I would, however, strongly consider adding an 'Advisory' notice to the MOT certificate. This would say something like "Nearside front windscreen has a stone chip".
What to do if you're worried before your test
If you've read this far and you're still a bit worried, don't be. There are simple steps you can take before you even book your MOT. First, do your own inspection. It's easy. Sit in the driver's seat and get a feel for where Zone A is. Remember, it's a 290mm wide band centred on the middle of your steering wheel. Use a ruler if you're unsure. Now, grab a coin. A 5p piece is about 18mm wide, and a penny is 20mm wide. Use these as a rough guide. A tiny chip that looks smaller than your little fingernail is almost certainly under 10mm. If you find a chip, measure it as best you can. If it's in Zo
What happens if you do fail
Let's say the worst happens and I have to fail your car on its windscreen. Please don't panic or worry – it's a common failure, and the process for putting it right is very clear. First, I will complete the test and then issue a VT30 'Refusal of an MOT Test Certificate'. This document will clearly list the defect – for example, "Windscreen has damage in excess of 10mm in Zone A". This is your official notification of the failure. At this point, your car may not have a valid MOT. If your old MOT certificate is still valid (i.e., you brought the car in for its test early), you can still drive th
Can I repair a chip myself before the MOT with a DIY kit? — You can, but I'd advise caution. DIY kits from car accessory shops can be a bit hit-and-miss. They can sometimes trap air or moisture, leading to a cloudy finish that still obstructs your view. A professional repairer uses a vacuum-sealed process to inject the resin, which gives a much clearer and stronger result that's far more likely to be invisible to an MOT tester. For the sake of avoiding a p
Does a cracked windscreen give me penalty points on my licence? — Failing the MOT itself does not result in penalty points. However, the MOT fail confirms that your vehicle is unroadworthy. If you are stopped by the police while driving with a windscreen that is cracked to a point of being dangerous, you can be prosecuted for driving a vehicle in a dangerous condition. This can lead to a fine of up to £2,500 and three penalty points on your licence. This is why
What about damage on the passenger side or at the very top of the windscreen? — The key thing to remember is the two zones. If the damage is on the passenger side, it falls into the 'rest of the swept area', where damage up to 40mm is allowed. This is quite a large area, about the size of a golf ball. Damage outside the area swept by the wipers altogether (like right at the very top edge or a blacked-out border) is not considered part of the test, as it doesn't obscure your v
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