10×12 slab: concrete by thickness
| Thickness | Cu ft | Cu yd | 80 lb bags | 60 lb bags |
|---|---|---|---|---|
| 3.5″ | 35.00 | 1.30 | 59 | 78 |
| 4″ | 40.00 | 1.48 | 67 | 89 |
| 5″ | 50.00 | 1.85 | 84 | 112 |
| 6″ | 60.00 | 2.22 | 100 | 134 |
No waste included in the table.
Worked example
10 ft × 12 ft = 120 sq ft. At 4 inches: 120 × 4 ÷ 12 = 40.00 cu ft, or 1.48 cubic yards. With 10% extra that is 1.63 yd³, or 74 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 10×12 slab?
67 × 80 lb or 89 × 60 lb bags at 4 inches thick, before waste.
How many yards of concrete for a 10×12 slab?
1.48 cubic yards at 4 inches; 2.22 at 6 inches.