Concrete for a 16×32 slab
6.32 cubic yards (313 × 80 lb bags)
for a 16×32 ft slab 4 inches thick: 170.7 cu ft. Bag counts include 10% extra; at 6 inches you need 9.48 yards.
A 16×32 foot slab covers 512 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 170.7 cubic feet of concrete, or 6.32 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 7 yards, roughly $1,155 before delivery fees, against $2,035 for 313 bags of 80 lb mix.
Concrete for a 16×32 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 4.74 | 128 | 235 | 313 | 470 |
| 4 in | 6.32 | 170.7 | 313 | 418 | 626 |
| 5 in | 7.9 | 213.3 | 392 | 522 | 783 |
| 6 in | 9.48 | 256 | 470 | 626 | 939 |
| 8 in | 12.64 | 341.3 | 626 | 835 | 1252 |
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 × 16 × 0.333 = 170.67 cu ft.
- Divide by 27 for cubic yards: 170.67 ÷ 27 = 6.321 cu yd.
- Add 10% and divide by the bag yield: 187.73 ÷ 0.6 = 313 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 6.32 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
- 15×32 slab
- 16×30 slab
- 14×32 slab
- 16×28 slab
- 16×36 slab
- 18×32 slab
- 16×26 slab
- 16×25 slab
- 12×32 slab
- 16×24 slab
- 16×40 slab
- 20×32 slab
Questions
- How many bags of concrete do I need for a 16×32 slab?
- At 4 inches thick, a 16×32 slab takes 313 bags of 80 lb concrete mix, 418 bags of 60 lb mix or 626 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 16×32 slab?
- 6.32 cubic yards at 4 inches thick, 7.9 at 5 inches and 9.48 at 6 inches, before adding extra for waste.
- How much does a 16×32 concrete slab cost?
- The concrete alone for a 4 inch 16×32 slab costs about $2,035 in 313 bags of 80 lb mix (at about $7 a bag) or about $1,155 for 7 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $3,072 to $6,144 for 512 sq ft.
- How much does a 16×32 slab weigh?
- About 12.4 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).