24×24 slab: concrete by thickness
| Thickness | Cu ft | Cu yd | 80 lb bags | 60 lb bags |
|---|---|---|---|---|
| 3.5″ | 168.00 | 6.22 | 280 | 374 |
| 4″ | 192.00 | 7.11 | 320 | 427 |
| 5″ | 240.00 | 8.89 | 400 | 534 |
| 6″ | 288.00 | 10.67 | 480 | 640 |
No waste included in the table.
Worked example
24 ft × 24 ft = 576 sq ft. At 4 inches: 576 × 4 ÷ 12 = 192.00 cu ft, or 7.11 cubic yards. With 10% extra that is 7.82 yd³, or 352 bags of 80 lb mix.
At over 1 cubic yard, compare the cost and labor of bags against a ready-mix delivery.
Assumes standard concrete mix bag yields: 80 lb ≈ 0.60 cu ft, 60 lb ≈ 0.45 cu ft. Check the yield on your bag. 1 cubic yard = 27 cubic feet.
Frequently asked questions
How many bags of concrete for a 24×24 slab?
320 × 80 lb or 427 × 60 lb bags at 4 inches thick, before waste.
How many yards of concrete for a 24×24 slab?
7.11 cubic yards at 4 inches; 10.67 at 6 inches.