Concrete for a 8×24 slab
2.37 cubic yards (118 × 80 lb bags)
for a 8×24 ft slab 4 inches thick: 64 cu ft. Bag counts include 10% extra; at 6 inches you need 3.56 yards.
A 8×24 foot slab covers 192 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 64 cubic feet of concrete, or 2.37 cubic yards. At this size you can mix 118 bags of 80 lb (about $767 and a long day of mixing) or order 2.75 yards of ready-mix (about $454, plus the short-load fee most suppliers charge under 3 to 4 yards).
Concrete for a 8×24 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 1.78 | 48 | 88 | 118 | 176 |
| 4 in | 2.37 | 64 | 118 | 157 | 235 |
| 5 in | 2.96 | 80 | 147 | 196 | 294 |
| 6 in | 3.56 | 96 | 176 | 235 | 352 |
| 8 in | 4.74 | 128 | 235 | 313 | 470 |
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: 24 × 8 × 0.333 = 64 cu ft.
- Divide by 27 for cubic yards: 64 ÷ 27 = 2.37 cu yd.
- Add 10% and divide by the bag yield: 70.4 ÷ 0.6 = 118 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 2.37 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
- 8×25 slab
- 8×22 slab
- 8×26 slab
- 8×20 slab
- 8×28 slab
- 6×24 slab
- 8×18 slab
- 8×30 slab
- 10×24 slab
- 8×16 slab
- 8×32 slab
- 5×24 slab
Questions
- How many bags of concrete do I need for a 8×24 slab?
- At 4 inches thick, a 8×24 slab takes 118 bags of 80 lb concrete mix, 157 bags of 60 lb mix or 235 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 8×24 slab?
- 2.37 cubic yards at 4 inches thick, 2.96 at 5 inches and 3.56 at 6 inches, before adding extra for waste.
- How much does a 8×24 concrete slab cost?
- The concrete alone for a 4 inch 8×24 slab costs about $767 in 118 bags of 80 lb mix (at about $7 a bag) or about $454 for 2.75 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $1,152 to $2,304 for 192 sq ft.
- How much does a 8×24 slab weigh?
- About 4.6 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).