How Much Concrete Do I Need for a Slab?
Concrete for common slab sizes at 4 inches thick, with 10% extra for spillage and an uneven subgrade. Pick a size for 5 and 6 inch thicknesses, weight and a bags vs ready-mix comparison.
| Slab size (ft) | Sq ft | Cubic yards | 80-lb bags | 60-lb bags |
|---|---|---|---|---|
| 4x4 | 16 | 0.22 | 10 | 14 |
| 5x5 | 25 | 0.34 | 16 | 21 |
| 6x6 | 36 | 0.49 | 22 | 30 |
| 8x8 | 64 | 0.87 | 40 | 53 |
| 8x10 | 80 | 1.09 | 49 | 66 |
| 10x10 | 100 | 1.36 | 62 | 82 |
| 10x12 | 120 | 1.63 | 74 | 98 |
| 10x20 | 200 | 2.72 | 123 | 163 |
| 12x12 | 144 | 1.96 | 88 | 118 |
| 12x16 | 192 | 2.61 | 118 | 157 |
| 12x20 | 240 | 3.26 | 147 | 196 |
| 14x14 | 196 | 2.66 | 120 | 160 |
| 16x16 | 256 | 3.48 | 157 | 209 |
| 16x20 | 320 | 4.35 | 196 | 261 |
| 20x20 | 400 | 5.43 | 245 | 326 |
| 20x24 | 480 | 6.52 | 294 | 392 |
| 24x24 | 576 | 7.82 | 352 | 470 |
| 24x30 | 720 | 9.78 | 440 | 587 |
Another size or shape? Use the concrete calculator, or measure an irregular area with the square footage calculator.