20 m² at 100 mm deep takes 2.0 m³ of gravel, about 3.2 tonnes; 200 sq ft at 4 inches takes 2.5 cubic yards, about 3.3 US tons.
| Area (m²) | 50 mm | 75 mm | 100 mm | 150 mm |
|---|---|---|---|---|
| 5 | 0.40 | 0.60 | 0.80 | 1.20 |
| 10 | 0.80 | 1.20 | 1.60 | 2.40 |
| 15 | 1.20 | 1.80 | 2.40 | 3.60 |
| 20 | 1.60 | 2.40 | 3.20 | 4.80 |
| 25 | 2.00 | 3.00 | 4.00 | 6.00 |
| 30 | 2.40 | 3.60 | 4.80 | 7.20 |
| 40 | 3.20 | 4.80 | 6.40 | 9.60 |
| 50 | 4.00 | 6.00 | 8.00 | 12.00 |
| 75 | 6.00 | 9.00 | 12.00 | 18.00 |
| 100 | 8.00 | 12.00 | 16.00 | 24.00 |
How it is computed
Volume = area × depth; weight = volume × 1,600 kg/m³, a typical bulk density for crushed stone and pea gravel. 1 m³ = 1.308 cu yd; 1 US ton = 907 kg. Heavier stone runs up to 1,800 kg/m³; enter your supplier's density in the calculator.
FAQ
How deep should a gravel driveway be?+
About 100 to 150 mm (4 to 6 in) of compacted base, plus 50 mm (2 in) of surface gravel. Paths need 50 to 75 mm (2 to 3 in).
Should I add extra for compaction?+
Yes, about 10 to 15% when the gravel will be compacted with a plate compactor.