chip guide
How Big a Windscreen Chip Can Be Repaired?
Images are illustrative onlyIn short: A windscreen chip is generally repairable if it is smaller than a 20c coin (about 28mm across) and any crack running from it is under about 15cm. Beyond those sizes, or if the chip is in the driver’s line of sight or within about 5cm of the edge of the glass, a replacement is usually needed. Location matters as much as size.
Key takeaways
- Under a 20c coin (about 28mm): usually repairable.
- Cracks under about 15cm can sometimes be stabilised; 15cm or longer means replace.
- Chips within about 5cm of the glass edge usually need a replacement.
- A chip in the driver’s sightline is often replaced even if small.
- Depth counts: through to the inner layer means replace.
The most common question after a stone chip is simply: is it too big to fix? Size is the first test, but it is not the only one, because where the chip sits on the glass matters just as much as how big it is. Here are the size and location rules Adelaide specialists work to.
The 20c coin test
The standard rule of thumb is a 20c coin, which is roughly 28mm across. Place one over the chip: if the damaged area disappears underneath it, the chip is small enough for resin to fill and bond, and a repair is very likely. If the chip pokes out past the coin, it is generally too large to repair reliably, and a replacement is the safe outcome.
| Damage | Rough size | Likely outcome |
|---|---|---|
| Bullseye / star chip | Under a 20c coin | Repairable |
| Combination chip | Around a 20c coin | Borderline, get it assessed |
| Chip with short leg | Crack under ~15cm | Often repairable |
| Long crack | 15cm or longer | Replace |
| Edge chip | Within ~5cm of the edge | Usually replace |
Why the edge of the glass is a special case
A chip near the edge of the windscreen is treated more cautiously than the same chip in the middle. The edges carry more of the structural load, and cracks that start there spread quickly and are harder to stabilise. As a general guide, damage within about 5cm of the edge often means a replacement even if the chip itself is small.
Location: the driver’s line of sight
A small chip that would be a simple repair anywhere else can still be a replacement if it sits directly in front of the driver. Resin repairs can leave slight optical distortion, and that is not acceptable in your primary viewing area. In SA, damage that obstructs the driver’s view can also make a vehicle defective, which is another reason a sightline chip is often replaced.
Depth: the layer that got hit
A windscreen is laminated: 2 sheets of glass around a plastic interlayer. If the impact only cracked the outer layer, resin can fill it. If it has reached the inner layer, the windscreen is structurally compromised and must be replaced regardless of how small the chip looks.
The Adelaide gravel-road factor
Drivers who regularly use the unsealed roads around the Adelaide Hills, the gravel around Kersbrook, Gumeracha, Cherry Gardens and the Fleurieu back roads, tend to collect several small chips rather than one. That matters, because more than 3 chips tips the glass towards replacement even when each one is individually tiny. If you drive gravel often, get chips fixed as they appear rather than letting them accumulate.
To gauge your specific chip, run it through the chip-or-replace checker, then get matched with a vetted Adelaide specialist who can confirm size, location and depth in person.
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