The whole calculation is three numbers and one division: length × width × depth, all in feet, divided by 27. That gives cubic yards, which is how bulk material is measured. Everything else — tons, bags, delivery loads — comes off that one figure.
The formula
cubic yards = (length_ft × width_ft × depth_ft) ÷ 27The only trap is depth. You’ll think about it in inches, but the formula wants feet, so divide by 12 first:
| Depth in inches | Depth in feet |
|---|---|
| 2 in | 0.167 ft |
| 3 in | 0.25 ft |
| 4 in | 0.333 ft |
| 6 in | 0.5 ft |
Worked example: a small parking pad
A 20 ft × 10 ft pad at 4 inches deep:
- Area: 20 × 10 = 200 sq ft
- Volume: 200 × 0.333 = 66.7 cubic feet
- Cubic yards: 66.7 ÷ 27 = 2.5 cubic yards
- Weight: 66.7 × 100 lb per cubic foot = 6,670 lb, or about 3.3 tons
- With 10% waste: order about 3.7 tons
The Gravel Calculator runs this for you and returns cubic yards, cubic feet, and tons together, so you have whichever unit your supplier quotes in.
How much area does gravel cover?
Working backwards from a delivery you’ve already priced:
| Depth | Coverage per cubic yard | Coverage per ton (crushed stone) |
|---|---|---|
| 1 in | 324 sq ft | 240 sq ft |
| 2 in | 162 sq ft | 120 sq ft |
| 3 in | 108 sq ft | 80 sq ft |
| 4 in | 81 sq ft | 60 sq ft |
| 6 in | 54 sq ft | 40 sq ft |
Converting cubic yards to tons
Suppliers often sell crushed stone by the ton and landscape rock by the yard, so you need to move between them:
tons = cubic_yards × 27 × density_lb_per_cubic_foot ÷ 2000Density depends on the stone:
| Material | Density (lb/ft³) | Tons per cubic yard |
|---|---|---|
| Crushed stone | 100 | 1.35 |
| Limestone | 96 | 1.30 |
| Pea gravel | 96 | 1.30 |
| River rock | 89 | 1.20 |
So 5 cubic yards of crushed stone is 5 × 27 × 100 ÷ 2,000 = 6.75 tons. As a rough field check, a cubic yard of gravel is a little over a ton and a third.
These are dry averages. Wet material can run 10–15% heavier, which matters when a supplier charges by weight and delivers after rain.
Depth by project type
| Project | Depth |
|---|---|
| Decorative bed or top dressing | 2 in |
| Garden path, walkway | 2–3 in |
| Refreshing an existing drive | 1–2 in |
| New driveway (all layers) | 8–12 in |
| Paver or patio base | 4–6 in |
| Shed or pad base | 4–6 in |
Driveways are the case people underestimate most, because the depth is built up in compacted layers rather than poured in one go — see how deep gravel should be for a driveway for the layer-by-layer breakdown.
Before you order
- Add waste. 10% is the standard allowance for compaction, settling, and uneven subgrade. On rough ground, use 15%.
- Odd shapes: break the area into rectangles and circles, calculate each, and add them. Curved beds are close enough if you use the average width.
- Delivery minimums: many suppliers won’t deliver under 1–3 tons, and a half-ton pickup legally carries well under a cubic yard of stone. Check both before planning a self-haul.
- Compaction: gravel settles roughly 20% under compaction. If you need 4 inches of finished depth, spread closer to 5.
Enter your dimensions in the Gravel Calculator to get cubic yards, tons, and a waste-adjusted order quantity in one pass.