How much concrete do I need?
Ready mix concrete is sold by the cubic yard and used for slabs, footings, driveways, walls, and steps.
Enter the length, width, and depth of your area above. The calculator shows cubic yards, cubic feet, an estimated weight in tons, and the number of 80 pound bags if you buy bagged concrete. Add a price per cubic yard and it also estimates the cost.
Cubic yard calculator for concrete
This cubic yard calculator for concrete works for any shape. Pick rectangle for most beds and slabs, circle for round areas, or trench for narrow runs. Open the price estimator under the calculator to add your supplier price, delivery fee, and tax. For a full cost breakdown, see the concrete cost calculator.
Concrete weight and bags per cubic yard
A planning value for concrete is 4,050 pounds per cubic yard, which is 2.02 US tons. Moisture, particle size, and compaction move that number, so treat it as a starting point.
| Measure | Value |
|---|---|
| Pounds per cubic yard | 4,050 |
| US tons per cubic yard | 2.02 |
| Kilograms per cubic yard | 1,837 |
| Cubic yards per US ton | 0.49 |
| Cubic feet per US ton | 13.33 |
| 80 pound bags per cubic yard | 45.0 |
How far does a cubic yard of concrete go?
Coverage depends only on depth. The deeper the layer, the less area a cubic yard covers. The suggested depth for concrete is 4 to 8 inches, and 4 inches is a common choice.
| Depth (inches) | Square feet covered | Square yards covered |
|---|---|---|
| 1 | 324 | 36.0 |
| 2 | 162 | 18.0 |
| 3 | 108 | 12.0 |
| 4 | 81 | 9.0 |
| 6 | 54 | 6.0 |
| 8 | 40 | 4.5 |
| 12 | 27 | 3.0 |
Concrete needed for common areas at 4 inches deep
| Area | Square feet | Cubic yards | US tons | 80 pound bags |
|---|---|---|---|---|
| 5 by 5 ft | 25 | 0.31 | 0.63 | 14 |
| 8 by 10 ft | 80 | 0.99 | 2.00 | 45 |
| 10 by 10 ft | 100 | 1.23 | 2.50 | 56 |
| 10 by 20 ft | 200 | 2.47 | 5.00 | 112 |
| 12 by 12 ft | 144 | 1.78 | 3.60 | 80 |
| 15 by 20 ft | 300 | 3.70 | 7.50 | 167 |
| 20 by 20 ft | 400 | 4.94 | 10.00 | 223 |
| 20 by 30 ft | 600 | 7.41 | 15.00 | 334 |
| 30 by 40 ft | 1,200 | 14.81 | 30.00 | 667 |
| 50 by 50 ft | 2,500 | 30.86 | 62.50 | 1,389 |
Worked example: 10 by 12 feet at 4 inches
The area is 10 feet times 12 feet, or 120 square feet. A depth of 4 inches is 0.33 feet. Volume is 120 times 0.33, which is 40.00 cubic feet. Divide by 27 to get 1.48 cubic yards. At 4,050 pounds per cubic yard that weighs about 3.00 US tons. With 10 percent extra, order 1.63 cubic yards.
Tips for ordering concrete
- Order 5 to 10 percent extra, because subgrade is never perfectly flat and forms bulge slightly.
- A standard 80 pound bag yields about 0.6 cubic feet, so one cubic yard needs roughly 45 bags.
- For anything over about 1.5 cubic yards, ready mix delivery is usually easier than mixing bags by hand.
Concrete cannot be returned or stored once mixed, so a small shortage costs far more than a small surplus.
Frequently asked questions
How many cubic yards of concrete do I need?
Multiply length, width, and depth in feet, then divide by 27. A 10 by 12 foot area at 4 inches deep needs about 1.48 cubic yards.
How much does a cubic yard of concrete weigh?
About 4,050 pounds, or 2.02 US tons, as a planning value. Ask your supplier for the exact figure.
How deep should concrete be?
Most projects use 4 to 8 inches. 4 inches is a common choice.
How many square feet does a cubic yard of concrete cover?
81 square feet at 4 inches deep, and 324 square feet at 1 inch.
How many bags of concrete make a cubic yard?
About 45 bags of the 80 pound size, which yields about 0.6 cubic feet each.