Over-excavation, spillage and uneven subgrade. 5-10% for formed work, 10-15% on rough ground.
Optional. Leave at zero to skip the cost estimate.
Material quantity estimate for planning and purchasing. Not structural engineering advice, not a bid, and not a code determination.
The conversion
A cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet. Because depth is almost always given in inches while length and width are in feet, the working formula is:
cubic yards = length (ft) × width (ft) × depth (in) ÷ 324
That 324 is just 27 × 12. It is the only number you need to do this in your head: a cubic yard covers 324 square feet one inch deep. From there, 162 square feet at 2 inches, 108 at 3 inches, 81 at 4 inches.
| Depth | Covers | Yards per 100 ft² | Yards per 1,000 ft² |
|---|---|---|---|
| 1 in | 324 ft² | 0.31 | 3.1 |
| 2 in | 162 ft² | 0.62 | 6.2 |
| 3 in | 108 ft² | 0.93 | 9.3 |
| 4 in | 81.0 ft² | 1.23 | 12.3 |
| 6 in | 54.0 ft² | 1.85 | 18.5 |
| 8 in | 40.5 ft² | 2.47 | 24.7 |
| 12 in | 27.0 ft² | 3.70 | 37.0 |
Cubic yards to cubic metres
One cubic yard is 0.7646 cubic metres; one cubic metre is 1.308 cubic yards. Concrete outside the US is ordered in cubic metres, which is why a "yard" and a "metre" of concrete are close enough to confuse but far enough apart to matter — a cubic metre is about 31% more concrete.
Common questions
How many cubic feet in a cubic yard?
27. A cubic yard is three feet on each side, and 3 x 3 x 3 = 27.
How do I calculate cubic yards from feet and inches?
Multiply length in feet by width in feet by depth in inches, then divide by 324. A 20 x 12 ft area at 4 inches deep is 20 x 12 x 4 / 324 = 2.96 cubic yards.
How much does a cubic yard cover?
324 square feet at 1 inch deep, 108 square feet at 3 inches, or 81 square feet at 4 inches. Divide 324 by your depth in inches.