Concrete Yard Calculator
Find how many cubic yards of concrete to order. Enter your measurements in feet and inches and the calculator rounds the order up to the next quarter yard.
How to calculate cubic yards of concrete
- Measure length, width and thickness.
- Convert everything to feet. Divide inches by 12, so 4 inches is 0.333 ft.
- Multiply the three numbers to get cubic feet.
- Divide by 27 to get cubic yards.
Example: a 20 ft × 24 ft driveway at 5 inches thick is 20 × 24 × 0.417 = 200 cubic feet. 200 ÷ 27 = 7.41 cubic yards. With 10% for waste that is 8.15, so you order 8.25 yards.
Square feet covered by one cubic yard
| Slab thickness | Square feet per cubic yard |
|---|---|
| 3 in | 108 |
| 4 in | 81 |
| 5 in | 65 |
| 6 in | 54 |
| 8 in | 40.5 |
To use the table, divide your square footage by the number for your thickness. A 400 sq ft patio at 4 inches is 400 ÷ 81 = 4.94 cubic yards.
Cubic yards for common slabs
| Slab size (ft) | 4 in thick | 5 in thick | 6 in thick |
|---|---|---|---|
| 10 × 10 | 1.23 | 1.54 | 1.85 |
| 12 × 12 | 1.78 | 2.22 | 2.67 |
| 16 × 16 | 3.16 | 3.95 | 4.74 |
| 20 × 20 | 4.94 | 6.17 | 7.41 |
| 20 × 24 | 5.93 | 7.41 | 8.89 |
| 24 × 24 | 7.11 | 8.89 | 10.67 |
| 30 × 30 | 11.11 | 13.89 | 16.67 |
Figures are exact volumes with no waste added.
Ordering ready-mix by the yard
- Suppliers sell in quarter-yard steps, so 3.48 yards becomes 3.5.
- Small orders often carry a short-load fee. Ask when you call.
- Tell the supplier the thickness and what the slab is for, so they can suggest the right mix.
- Under about 1 yard, bags may be simpler. See how many bags are in a yard.
Frequently asked questions
How do I calculate yards of concrete?
Multiply length × width × thickness in feet to get cubic feet, then divide by 27. A 12 ft × 12 ft slab at 4 inches is 12 × 12 × 0.333 = 48 cubic feet, or 1.78 cubic yards.
How many square feet does a yard of concrete cover?
81 square feet at 4 inches thick, 65 square feet at 5 inches and 54 square feet at 6 inches.
How many yards of concrete are in a truck?
A standard ready-mix truck carries about 10 cubic yards. Sizes vary, so ask your supplier.
How much is a cubic yard of concrete in cubic feet?
27 cubic feet. A cubic yard is a cube 3 ft on each side.
Should I round up my concrete order?
Yes. Add 5% to 10% for waste, then round up to the next quarter yard, which is how most suppliers sell it.