How it's worked out
- Volume: 20 × 40 × 4 in ÷ 12 = 266.7 cu ft
- Cubic yards: 266.7 ÷ 27 = 9.88 yd³
- Tons: 9.88 × 1.4 tons per yard = 13.8 tons
20x40 driveway at other depths
| Depth | Cubic yards | Tons (approx.) | With 10% extra |
|---|---|---|---|
| 2 in | 4.94 | 6.9 | 7.6 |
| 4 in | 9.88 | 13.8 | 15.2 |
| 6 in | 14.81 | 20.7 | 22.8 |
A new driveway is usually built in layers: 4 to 6 inches of large crushed stone for the base, then 2 to 3 inches of smaller top stone. Refreshing an existing driveway takes about 2 inches. The 1.4 tons per yard figure is typical for gravel; ask your supplier for theirs.
Other common sizes
- 10 × 30 ft driveway
- 12 × 50 ft driveway
- 12 × 60 ft driveway
- 12 × 100 ft driveway
- 20 × 40 ft driveway
- 20 × 50 ft driveway
More detail: How Much Gravel Do I Need for a Driveway?