How Much Concrete for a 30x32 Garage Slab?
A 30 by 32 foot garage slab is 960 square feet. How much concrete for a 30x32 garage slab at the common 5-inch thickness: about 14.81 cubic yards. Most people order 16.50 yards to cover waste and an uneven base.
Concrete calculator →The math for a 30x32 garage slab
- Area: 30 ft × 32 ft = 960 sq ft.
- Thickness in feet: 5 in ÷ 12 = 0.417 ft.
- Volume: 960 × 0.417 = 400.0 cubic feet.
- Cubic yards: 400.0 ÷ 27 = 14.81 yd³.
- With 10% extra: 16.30 yd³.
The concrete calculator runs the same steps for any size and thickness.
Related: How Much Concrete for a 12x20 Garage Slab?
Concrete for a 30x32 garage slab by thickness
| Thickness | Cubic feet | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags |
|---|---|---|---|---|---|
| 4 in | 320.0 | 11.85 | 13.04 | 534 | 712 |
| 5 in | 400.0 | 14.81 | 16.30 | 667 | 889 |
| 6 in | 480.0 | 17.78 | 19.56 | 800 | 1,067 |
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
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.
Related: How Much Concrete for a 12x24 Garage Slab?
Ordering ready-mix
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.
Prep before the pour
Uneven ground is the main reason pours run short. Every half inch of extra depth across the garage 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
Plan the joints before the pour. Panels close to square crack less than long, narrow ones, and joint spacing around 10 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 30x32 garage slab at 4 inches?
About 11.85 cubic yards, or 13.04 with 10 percent extra.
How many yards for a 30x32 garage slab at 6 inches?
About 17.78 cubic yards.
How many 80 lb bags for a 30x32 garage slab?
About 534 bags at 4 inches thick, before any waste allowance.
How many square feet is a 30x32 garage slab?
960 square feet.
Should I add extra for waste?
Yes. Adding 5 to 10 percent covers uneven base, spillage and form bulges.
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 28x30 Garage Slab?
- How Much Concrete for a 30x30 Garage Slab?
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