Concrete for a 24 × 30 slab
Short answer
A 24 × 30 ft slab at 4" thick needs about 8.89 cubic yards of concrete — roughly 440 80-lb or 587 60-lb pre-mix bags (including 10% waste).
Concrete
8.89 yd³
80-lb bags
440
60-lb bags
587
40-lb bags
880
24 × 30 slab at 4" thick
A 24 × 30 ft slab is 720 square feet. At the standard 4-inch thickness that works out to 240 cubic feet, or 8.89 cubic yards including a 10% waste allowance. For a driveway or anything bearing vehicle loads, step up to 5–6 inches.
Different size or thickness?
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Frequently asked questions
How much concrete for a 24 × 30 slab?
A 24 × 30 ft slab at 4" thick needs about 8.89 cubic yards (240 cubic feet), including a 10% waste allowance.
How many bags of concrete for a 24 × 30 slab?
About 440 80-lb bags, 587 60-lb bags, or 880 40-lb bags. Above roughly 1 cubic yard it is usually cheaper to order ready-mix than to buy bags.
Is a 4-inch slab thick enough?
Four inches is standard for patios, walkways, and shed floors. Go to 5–6 inches for driveways or anything carrying vehicle loads. Change the thickness in the calculator to see the new amount.