Area and depth to cubic yards, then to tons
The 324 folds together the two unit changes (inches to feet, cubic feet to cubic yards) into one number. Once you have the volume, weight is tons = cubic yards × density, and gravel density is about 1.4 tons per cubic yard. So a yard of gravel is close to a ton and a half.
Coverage by depth (crushed gravel, 1.5 t/yd³)
| Area | 2" deep | 4" deep | 6" deep |
|---|---|---|---|
| 100 sq ft | 0.6 yd³ | 1.2 yd³ | 1.85 yd³ |
| 500 sq ft | 3.1 yd³ | 6.2 yd³ | 9.3 yd³ |
| 1,000 sq ft | 6.2 yd³ | 12.3 yd³ | 18.5 yd³ |
| 2,000 sq ft | 12.3 yd³ | 24.7 yd³ | 37 yd³ |
To convert any row to tons, multiply by about 1.5. That 4-inch, 1,000 sq ft driveway of 12.3 yd³ is roughly 18 tons of stone.
Density depends on the stone, so order a bit extra
- Pea gravel — rounded and decorative, about 1.4 t/yd³. Good for patios and paths, not for load-bearing bases.
- Crushed stone — angular, locks together, about 1.5 t/yd³. The standard driveway and base material.
- Add 10–15% — loose gravel settles and compacts in the first year, so round your order up rather than down.
Common questions
How do I work out how much gravel I need?
Multiply the area in square feet by the depth in inches, then divide by 324 to get cubic yards. A 600 sq ft driveway at 4 inches is (600 x 4) / 324 = 7.4 cubic yards.
How much does a cubic yard of gravel weigh?
Crushed gravel runs about 1.3 to 1.7 tons per cubic yard, so 1.4 to 1.5 tons is the usual planning figure. Pea gravel is a touch lighter and wet gravel is heavier.
How deep should a gravel driveway be?
About 4 to 6 inches for a driveway, and 2 to 3 inches for a decorative patio or path. Roads go 6 to 8 inches. Deeper drains better and lasts longer.
Should I order extra gravel?
Yes. Add 10 to 15% because loose material compacts as it settles in the first year. Rounding a 7.4 cubic yard order up to 8 covers it.
