- ~10m²per 850kg bag at 50mm
- 20mmgravel for driveways
- 50mmgravel depth, no deeper
- 150mmMOT sub-base underneath
Gravel by driveway size
20mm gravel, 50mm deep, 5% extra, 850kg bulk bags.
| Driveway | Area | Gravel | Bulk bags |
|---|---|---|---|
| 3 × 6 m (one car) | 18 m² | 1.6 t | 2 |
| 5 × 6 m | 30 m² | 2.6 t | 4 |
| 6 × 8 m (two cars) | 48 m² | 4.2 t | 5 |
| 10 × 5 m | 50 m² | 4.3 t | 6 |
The sum
Tonnes = area (m²) × depth (m) × 1.65 × 1.05
30m² at 50mm: 30 × 0.05 × 1.65 × 1.05 = 2.6 t
The gravel is the easy part. The sub-base under it takes far more material: the MOT Type 1 calculator works out the tonnes, and the excavation calculator the dig and skip.
