How gravel is calculated
First find the volume, then turn it into weight with the material's density. Quarries and yards sell by the ton or by the cubic yard, so you get both.
Tons = cubic yards × density (tons per cubic yard)
Worked example
A 10 × 10 ft area, 4 inches deep: 10 × 10 × 4 ÷ 12 = 33.3 cubic feet, ÷ 27 = 1.235 cubic yards. At 1.42 tons per cubic yard, that's 1.235 × 1.42 = 1.75 tons (about 3,506 lb).
The densities used
Gravel and sand don't have one fixed weight. It depends on the rock, the size of the pieces, how tightly they're packed and how wet they are. The presets come from the bulk densities published by The Engineering ToolBox:
| Material | lb per cu ft | Tons per cu yd |
|---|---|---|
| Gravel, dry | 105 | 1.42 |
| Sand, dry | 100 (range 80–100) | 1.35 |
| Sand, wet | 120 | 1.62 |
| Crushed stone | about 104 (crushed limestone 85–95, crushed rock up to 134) | 1.4 |
To convert, tons per cubic yard = lb per cu ft × 27 ÷ 2,000. Your supplier knows the real weight of what they sell, so ask them and type it into the density box.
Typical depths
- Walkways and patios: about 2 to 3 inches of decorative gravel or pea gravel.
- Driveways: often 4 to 6 inches of base stone with a top layer; heavy traffic or soft soil needs more.
- Base under pavers or a slab: follow the paver maker's or your plan's spec.
Limitations
Loose stone compacts when it's tamped or driven on, so a compacted base needs more than the finished depth suggests; that's what the "Extra" box is for. Uneven ground also eats material. Tons here are US short tons (2,000 lb); metric tonnes are shown too.