Concrete
How Many Square Feet Does a Yard of Concrete Cover?
One cubic yard of concrete covers 81 square feet at 4 inches thick. Divide 324 by the thickness in inches to get the square feet one yard covers at any thickness.
By Kumar Baniya, MEng in Structural Engineering (University of Leeds) · Published
How many square feet does a yard of concrete cover at 4 inches?
81 square feet. A cubic yard is 27 cubic feet, and 4 inches is one third of a foot, so 27 ÷ 0.333 = 81 sq ft — for example a 9 × 9 ft square. The shortcut is 324 ÷ thickness in inches.
How much area does a yard cover at other thicknesses?
| Thickness | Square feet per cubic yard | Cubic yards per 100 sq ft |
|---|---|---|
| 2 in | 162.0 | 0.62 |
| 3 in | 108.0 | 0.93 |
| 3.5 in | 92.6 | 1.08 |
| 4 in | 81.0 | 1.23 |
| 5 in | 64.8 | 1.54 |
| 6 in | 54.0 | 1.85 |
| 8 in | 40.5 | 2.47 |
| 10 in | 32.4 | 3.09 |
| 12 in | 27.0 | 3.70 |
Thicknesses are listed for the arithmetic only; the right thickness for a slab depends on its use, the base and local building codes.
How many yards of concrete do I need for a given area?
Reverse the formula: cubic yards = square feet × thickness (in) ÷ 324. A 400 sq ft patio at 4 in needs 400 × 4 ÷ 324 = 4.94 yd³. The square feet to cubic yards calculator does this for any area and depth.
How much does half a yard of concrete cover?
Half a cubic yard covers 40.5 sq ft at 4 in — half of 81. Two yards cover 162 sq ft at 4 in, and three yards cover 243 sq ft.
How much concrete is needed per square foot?
Each square foot at 4 in thick needs 4 ÷ 12 = 0.333 ft³, which is 0.0123 yd³ — about 0.56 of an 80 lb bag of QUIKRETE Concrete Mix (0.60 ft³ yield). At 6 in, each square foot needs 0.5 ft³.
Does a slab formed with 2 × 4s really measure 4 inches?
No. A nominal 2 × 4 is 3.5 in wide, so a slab formed with it is 3.5 in thick and one cubic yard covers 92.6 sq ft, not 81. Use the actual form height in your calculation.
Related calculations
For the full method with footings and columns, see how to calculate yards of concrete. For bagged mix, bags of concrete per yard lists every bag size.