How Much Concrete for a 12x32 Slab?
A 12 by 32 foot slab is 384 square feet. How much concrete for a 12x32 slab at the common 4-inch thickness: about 4.74 cubic yards. Most people order 5.25 yards to cover waste and an uneven base.
Concrete calculator →The math for a 12x32 slab
- Area: 12 ft × 32 ft = 384 sq ft.
- Thickness in feet: 4 in ÷ 12 = 0.333 ft.
- Volume: 384 × 0.333 = 128.0 cubic feet.
- Cubic yards: 128.0 ÷ 27 = 4.74 yd³.
- With 10% extra: 5.21 yd³.
The concrete calculator runs the same steps for any size and thickness.
Related: How Much Concrete for a 12x20 Slab?
Concrete for a 12x32 slab by thickness
| Thickness | Cubic feet | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags |
|---|---|---|---|---|---|
| 4 in | 128.0 | 4.74 | 5.21 | 214 | 285 |
| 5 in | 160.0 | 5.93 | 6.52 | 267 | 356 |
| 6 in | 192.0 | 7.11 | 7.82 | 320 | 427 |
Bag counts assume about 0.60 cubic feet per 80 lb bag and 0.45 per 60 lb bag, rounded up.
Thickness for this job
Four inches is the usual thickness for patios, walks and shed floors. Slabs that carry cars or a heavy hot tub are often poured at 5 to 6 inches, and edges are sometimes thickened where loads concentrate.
Related: How Much Concrete for a 12x24 Slab?
Truck or bags?
Ready-mix is priced and batched by the cubic yard (27 cubic feet). Plants commonly add a small-load fee when an order is under a set minimum, so ask about it when you call. Ordering a little extra costs far less than a second truck.
Getting the ground ready
Uneven ground is the main reason pours run short. Every half inch of extra depth across the slab adds concrete you did not plan for. Screed the base flat, check it with a string line and set the forms to finished height before the truck arrives.
Keeping cracks under control
Cut or tool control joints so the slab cracks where you want it to. A common rule is spacing them, in feet, at no more than two to three times the slab thickness in inches, so about 12 feet apart for a 4-inch slab, and about a quarter of the slab depth deep.
Questions people ask
How many yards of concrete for a 12x32 slab at 4 inches?
About 4.74 cubic yards, or 5.21 with 10 percent extra.
How many yards for a 12x32 slab at 6 inches?
About 7.11 cubic yards.
How many 80 lb bags for a 12x32 slab?
About 214 bags at 4 inches thick, before any waste allowance.
How many square feet is a 12x32 slab?
384 square feet.
How many 80 lb bags make a cubic yard?
About 45. Each 80 lb bag yields roughly 0.6 cubic feet, and a cubic yard is 27 cubic feet.
When is bagged concrete practical?
Usually for jobs under about a cubic yard. Beyond that, mixing dozens of bags by hand gets slow and batches may not blend well.
Related guides
- How Much Area Does a Yard of Concrete Cover?
- How Many Bags of Concrete in a Yard? 40, 60, 80 lb
- Gravel Base Under a Concrete Slab: Depth and Tons
- How Many Yards in a Concrete Truck? Mixer Sizes
- Concrete Short Load Fee: What It Is and How to Cut It
- 60 lb vs 80 lb Concrete Bags: Yield, Count, and Cost
- Rebar vs Wire Mesh in a Slab: Which One to Use
- Cost to Pour a Concrete Slab: Per Square Foot
- How Much Concrete for a 12x28 Slab?
- How Much Concrete for a 12x30 Slab?
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