AsphaltTons.com — asphalt tonnage calculator

How Much Concrete for a 24x32 Garage Slab?

A 24 by 32 foot garage slab is 768 square feet. How much concrete for a 24x32 garage slab at the common 5-inch thickness: about 11.85 cubic yards. Most people order 13.25 yards to cover waste and an uneven base.

Concrete calculator →

The math for a 24x32 garage slab

  1. Area: 24 ft × 32 ft = 768 sq ft.
  2. Thickness in feet: 5 in ÷ 12 = 0.417 ft.
  3. Volume: 768 × 0.417 = 320.0 cubic feet.
  4. Cubic yards: 320.0 ÷ 27 = 11.85 yd³.
  5. With 10% extra: 13.04 yd³.

The concrete calculator runs the same steps for any size and thickness.

Concrete for a 24x32 garage slab by thickness

ThicknessCubic feetCubic yardsYards +10%80 lb bags60 lb bags
4 in256.09.4810.43427569
5 in320.011.8513.04534712
6 in384.014.2215.64640854

Bag counts assume about 0.60 cubic feet per 80 lb bag and 0.45 per 60 lb bag, rounded up.

How thick to pour it

Garage floors are commonly 4 to 6 inches thick; 5 inches is a practical middle for cars and light trucks, and 6 inches suits heavier vehicles or a shop with equipment. Check local code, since some areas set a minimum.

Truck or bags?

A cubic yard of concrete is 27 cubic feet and weighs roughly 4,000 pounds. Most ready-mix trucks carry up to about 9 to 10 yards, though local trucks and rules vary. If your total is under a yard or two, bagged mix or a short-load supplier may be cheaper.

Getting the ground ready

Under the slab, most residential pours sit on about 4 inches of compacted gravel. The base spreads the load, drains water away and keeps the garage slab from cracking as the soil freezes and thaws. Compact the base in thin lifts, and dampen it just before the pour so it does not pull water out of the mix.

Joints, mesh and rebar

Plan the joints before the pour. Panels close to square crack less than long, narrow ones, and joint spacing around 8 feet is typical for a 4-inch slab. Cut joints with a groover while the concrete is soft or with a saw within the first day.

Questions people ask

How many yards of concrete for a 24x32 garage slab at 4 inches?

About 9.48 cubic yards, or 10.43 with 10 percent extra.

How many yards for a 24x32 garage slab at 6 inches?

About 14.22 cubic yards.

How many 80 lb bags for a 24x32 garage slab?

About 427 bags at 4 inches thick, before any waste allowance.

How many square feet is a 24x32 garage slab?

768 square feet.

How much does a cubic yard of concrete weigh?

Roughly 4,000 pounds, or about 2 tons, for normal-weight concrete.

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

Open the concrete calculator → Asphalt tonnage calculator →

As an Amazon Associate, AsphaltTons.com earns from qualifying purchases. Product links below are sponsored.

Related answers