How to calculate how much gravel you need
Here it is with your numbers:
- Change the depth to feet: 3 in ÷ 12 = 0.25 ft.
- Multiply length × width × depth: 20 × 10 × 0.25 = 50 cu ft.
- Divide by 27 to get cubic yards: 50 ÷ 27 = 1.8519 cu yd.
- Round to two decimal places: 1.85 cu yd.
- Multiply by the weight of the stone: 50 ÷ 27 × 1.25 = 2.3148, which rounds to 2.31 tons.
It means you need 1.85 cubic yards, which weighs 2.31 tons. Order 2 cubic yards so you don't run short.
Gravel is sold by volume (cubic yards) or by weight (tons). 1 cubic yard is 27 cubic feet, a box 3 ft on every side, and a ton here is the US short ton of 2,000 pounds. For a round bed, use the distance all the way across and halve it.
Source NIST Handbook 44 (2026) · Appendix C, General Tables of Units of Measurement ↗Common Core State Standards · Grade 5, volume V = l × w × h (5.MD.C.5) ↗Common Core State Standards · Grade 8, volume of a cylinder (8.G.C.9) ↗
How much does a cubic yard of gravel weigh?
It depends on the stone and on whether it is packed down. The Missouri Department of Transportation lists these weights, in tons per cubic yard. Use the loose weight for gravel you tip and rake, and the compacted weight for a base you will pack down with a plate compactor, because packing squeezes more stone into the same space.
| Stone | Loose | Compacted |
|---|---|---|
| Trap rock | 1.30 – 1.39 | 1.65 – 1.77 |
| Granite or limestone | 1.21 – 1.30 | 1.53 – 1.65 |
| Sandstone | 1.11 – 1.25 | 1.42 – 1.59 |
| Sand | 1.32 – 1.48 | 1.42 – 1.59 |
| Slag | 0.74 – 1.16 | 0.95 – 1.48 |
Our starting weight, 1.25 tons per cubic yard, is the middle of the loose granite or limestone range (2,500 pounds). Your supplier's own figure is the best one to use.
Source Missouri DOT Engineering Policy Guide · Highway Maintenance Tables and Conversion Factors, page 5 ↗
FAQs
How much gravel do I need?
Multiply the length, width and depth in feet, then divide by 27 to get cubic yards. A path 20 ft long and 10 ft wide, 3 inches (0.25 ft) deep, is 20 × 10 × 0.25 = 50 cubic feet, which is 1.85 cubic yards. Order 2 cubic yards so you don't run short.
Source NIST Handbook 44 (2026) · Appendix C, General Tables of Units of Measurement ↗
How much does a yard of gravel weigh?
A cubic yard of loose crushed granite or limestone weighs 2,410 – 2,590 pounds, about 1.2 – 1.3 tons, in the Missouri DOT's table. Packed down, the same stone weighs 3,060 – 3,300 pounds a cubic yard.
Source Missouri DOT Engineering Policy Guide · Highway Maintenance Tables and Conversion Factors, page 5 ↗
How many yards are in a ton of gravel?
At 1.25 tons per cubic yard (loose granite or limestone), a ton is 0.8 cubic yards: divide 1 by the weight of a cubic yard. Heavier stone gives fewer yards per ton, so ask your supplier for their figure.
Sources
- NIST Handbook 44 (2026): Appendix C, General Tables of Units of Measurement
- Missouri DOT Engineering Policy Guide: Highway Maintenance Tables and Conversion Factors, page 5
- Common Core State Standards: Grade 5, volume V = l × w × h (5.MD.C.5)
- Common Core State Standards: Grade 8, volume of a cylinder (8.G.C.9)