Concrete for a 8×32 slab
3.16 cubic yards (157 × 80 lb bags)
for a 8×32 ft slab 4 inches thick: 85.3 cu ft. Bag counts include 10% extra; at 6 inches you need 4.74 yards.
A 8×32 foot slab covers 256 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 85.3 cubic feet of concrete, or 3.16 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 3.5 yards, roughly $578 before delivery fees, against $1,021 for 157 bags of 80 lb mix.
Concrete for a 8×32 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 2.37 | 64 | 118 | 157 | 235 |
| 4 in | 3.16 | 85.3 | 157 | 209 | 313 |
| 5 in | 3.95 | 106.7 | 196 | 261 | 392 |
| 6 in | 4.74 | 128 | 235 | 313 | 470 |
| 8 in | 6.32 | 170.7 | 313 | 418 | 626 |
Bag counts include 10% extra for spillage and uneven ground. Cubic yards and cubic feet are the exact volume.
How it’s worked out
- Convert the thickness to feet: 4 in ÷ 12 = 0.333 ft.
- Multiply length × width × thickness: 32 × 8 × 0.333 = 85.33 cu ft.
- Divide by 27 for cubic yards: 85.33 ÷ 27 = 3.16 cu yd.
- Add 10% and divide by the bag yield: 93.87 ÷ 0.6 = 157 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 3.16 cubic yards. For driveways and anything that carries a vehicle, go to 5 or 6 inches and add rebar or wire mesh.
Change the numbers
Other slab sizes
- 8×30 slab
- 8×28 slab
- 8×36 slab
- 8×26 slab
- 8×25 slab
- 6×32 slab
- 8×24 slab
- 8×40 slab
- 10×32 slab
- 8×22 slab
- 5×32 slab
- 8×20 slab
Questions
- How many bags of concrete do I need for a 8×32 slab?
- At 4 inches thick, a 8×32 slab takes 157 bags of 80 lb concrete mix, 209 bags of 60 lb mix or 313 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 8×32 slab?
- 3.16 cubic yards at 4 inches thick, 3.95 at 5 inches and 4.74 at 6 inches, before adding extra for waste.
- How much does a 8×32 concrete slab cost?
- The concrete alone for a 4 inch 8×32 slab costs about $1,021 in 157 bags of 80 lb mix (at about $7 a bag) or about $578 for 3.5 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $1,536 to $3,072 for 256 sq ft.
- How much does a 8×32 slab weigh?
- About 6.2 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).