Supply MathCubic yards for common slab sizes (+10%)
| Slab size | 4 in | 5 in | 6 in |
|---|---|---|---|
| 10 × 10 ft | 1.36 yd³ | 1.7 yd³ | 2.04 yd³ |
| 12 × 12 ft | 1.96 yd³ | 2.44 yd³ | 2.93 yd³ |
| 10 × 20 ft | 2.72 yd³ | 3.4 yd³ | 4.07 yd³ |
| 12 × 24 ft | 3.91 yd³ | 4.89 yd³ | 5.87 yd³ |
| 20 × 20 ft | 5.43 yd³ | 6.79 yd³ | 8.15 yd³ |
| 24 × 24 ft | 7.82 yd³ | 9.78 yd³ | 11.73 yd³ |
| 30 × 30 ft | 12.22 yd³ | 15.28 yd³ | 18.33 yd³ |
Typical slab thickness
- 4 in: patios, walkways, shed and hot-tub pads.
- 5–6 in: driveways, garage floors, RV pads.
- Thickened edges: many slabs are 8–12 in at the perimeter. Add them with the footing calculator.
Frequently asked questions
How much concrete do I need for a 10x10 slab?
At 4 inches thick, a 10 × 10 ft slab is about 1.24 cubic yards, or 1.36 yd³ with 10% extra: roughly 62 bags of 80 lb concrete. At 6 inches it’s 2.04 yd³.
How thick should a patio or shed slab be?
4 inches is standard for patios, sidewalks and shed floors on well-compacted base. Use 5–6 inches for driveways and garage floors, thicker for heavy loads, and follow local code.
Do I need gravel under a concrete slab?
Usually yes: 4 inches of compacted gravel base improves drainage and helps prevent cracking. Use the gravel calculator to size it.