Concrete for an 8×10 slab at different thicknesses
The slab covers 80 square feet. Every extra inch of thickness adds about 0.25 cubic yards. Quantities below include 10% for waste.
| Thickness | Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|
| 3.5 in | 0.95 | 43 | 58 | 86 |
| 4 in | 1.09 | 49 | 66 | 98 |
| 5 in | 1.36 | 62 | 82 | 123 |
| 6 in | 1.63 | 74 | 98 | 147 |
| 8 in | 2.17 | 98 | 131 | 196 |
Bags or ready-mix for this size?
At 1.09 cubic yards you are in the gray zone between bags and a truck. 49 bags of 80 lb weigh about 3,920 lb in total — get a ready-mix quote (ask about short-load fees) and compare it with the bag price before deciding.
How heavy is an 8×10 slab?
Normal-weight concrete weighs about 150 lb per cubic foot, so a 4-inch 8×10 slab weighs roughly 4,000 lb (2 tons) once cured. Make sure your base is compacted gravel on firm, undisturbed soil.
The math
Common questions
How many 80 lb bags of concrete for an 8x10 slab?
49 bags for a 4-inch slab including 10% extra (45 with no extra). At 6 inches thick you need 74 bags.
How many yards of concrete for an 8x10 slab 6 inches thick?
1.63 cubic yards including 10% extra, or 1.48 yards exactly.
How many 60 lb bags for an 8x10 slab?
66 bags of 60 lb concrete for a 4-inch slab with 10% extra.
Want the full method, tips and other sizes? See the concrete calculator guide.