Concrete for a 15×32 slab
5.93 cubic yards (294 × 80 lb bags)
for a 15×32 ft slab 4 inches thick: 160 cu ft. Bag counts include 10% extra; at 6 inches you need 8.89 yards.
A 15×32 foot slab covers 480 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 160 cubic feet of concrete, or 5.93 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 6.75 yards, roughly $1,114 before delivery fees, against $1,911 for 294 bags of 80 lb mix.
Concrete for a 15×32 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 4.44 | 120 | 220 | 294 | 440 |
| 4 in | 5.93 | 160 | 294 | 392 | 587 |
| 5 in | 7.41 | 200 | 367 | 489 | 734 |
| 6 in | 8.89 | 240 | 440 | 587 | 880 |
| 8 in | 11.85 | 320 | 587 | 783 | 1174 |
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 × 15 × 0.333 = 160 cu ft.
- Divide by 27 for cubic yards: 160 ÷ 27 = 5.926 cu yd.
- Add 10% and divide by the bag yield: 176 ÷ 0.6 = 294 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 5.93 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
- 15×30 slab
- 14×32 slab
- 16×32 slab
- 15×28 slab
- 15×36 slab
- 15×26 slab
- 12×32 slab
- 18×32 slab
- 15×25 slab
- 15×24 slab
- 15×40 slab
- 15×22 slab
Questions
- How many bags of concrete do I need for a 15×32 slab?
- At 4 inches thick, a 15×32 slab takes 294 bags of 80 lb concrete mix, 392 bags of 60 lb mix or 587 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 15×32 slab?
- 5.93 cubic yards at 4 inches thick, 7.41 at 5 inches and 8.89 at 6 inches, before adding extra for waste.
- How much does a 15×32 concrete slab cost?
- The concrete alone for a 4 inch 15×32 slab costs about $1,911 in 294 bags of 80 lb mix (at about $7 a bag) or about $1,114 for 6.75 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $2,880 to $5,760 for 480 sq ft.
- How much does a 15×32 slab weigh?
- About 11.6 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).