Bags or a truck?
At this size a ready-mix truck is the sensible choice. Mixing 160 bags by hand is a long, heavy day, and the first batches start to set before the last ones are placed.
Concrete slab charts · 12 × 24 ft
How much concrete for a 12×24 slab?
A 12 × 24 ft slab 4 inches thick needs 3.56 cubic yards of concrete (96.0 cubic feet), or about 160 bags of 80 lb premix. Add 5–10% for waste. Other thicknesses are in the table, or adjust the calculator below.
Units
12 × 24 ft slab by thickness
Exact volumes without waste. Bag counts are rounded up.
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | Metric |
|---|---|---|---|---|---|
| 3 in | 2.67 yd³ | 72.0 ft³ | 120 | 160 | 2.04 m³ |
| 4 in | 3.56 yd³ | 96.0 ft³ | 160 | 214 | 2.72 m³ |
| 5 in | 4.44 yd³ | 120.0 ft³ | 200 | 267 | 3.40 m³ |
| 6 in | 5.33 yd³ | 144.0 ft³ | 240 | 320 | 4.08 m³ |