How deep should a driveway be?
A driveway is two layers, not one: a compacted sub-base that carries the load, and a surface that sits on top of it. Each has its own depth and its own material, and ordering them together is what runs people short.
| Material | Depth | In inches | Where the depth comes from |
|---|---|---|---|
| MOT Type 1 | 150mm | 5.9 in | Mainland Aggregates: 150mm depth when used as a driveway sub-base for car traffic. |
| Gravel | 40 to 50mm | 1.6 to 2 in | Mainland Aggregates: gravel goes over a compacted sub-base, not straight onto soil. |
| Aggregate | 40 to 50mm | 1.6 to 2 in | Mainland Aggregates: spread over a compacted sub-base such as Type 1. |
| Concrete | 150mm | 5.9 in | Quikrete: 6 inches is the upper end of its small-slab range, for the heaviest loads it covers. |
Working out the quantity once you have the depth
Multiply the area by the depth for a volume, then by the material's bulk density for a weight. Each calculator below does it in the units that material is sold in, and each shows the density range its figure came from.
- MOT Type 1 calculator
- Paver base calculator
- Gravel calculator
- Aggregate calculator
- Concrete calculator
- Crushed stone calculator
Materials without a published depth for this use
No supplier read for this site publishes a laid depth for road base and crushed stone on a driveway, so none is stated here. Their calculators take whatever depth you enter.