How Many Bags of Concrete for a 24x24 Slab? (2026 Guide)

The concrete math for a 24×24 slab

A 24×24 ft slab is 576 sq ft. To get the volume in cubic feet, multiply the area by the thickness in inches and divide by 12: 576 × 4 ÷ 12 = 192 cu ft at the standard 4-in depth. Each extra inch of thickness adds 48 cu ft (576 ÷ 12). An 80-lb bag of concrete mix yields about 0.6 cu ft, so divide the volume by 0.6 to count bags.

Here's the full picture for the common slab thicknesses:

Read across: a standard 4-in slab takes 320 bags of 80-lb mix, or 7.1 yd³ of ready-mix. Bags are the right tool for footings and small pads — not for 576 sq ft. At 6 in the count climbs to 480 bags, and a slab that thick is usually a garage or shop floor that needs truck-batched concrete anyway. The concrete calculator gives the same totals for your exact depth.

Worked example: a 4-in slab, step by step

1. Find the volume in cubic feet

The slab is 576 sq ft × 0.333 ft (4 in) = 192 cu ft of concrete.

2. Count the 80-lb bags

Each 80-lb bag makes about 0.6 cu ft, so 192 ÷ 0.6 = 320 bags.

3. Add up what 320 bags really means

320 bags weigh 320 × 80 = 25,600 lb — about 12.8 tons — and arrive as roughly 8 pallets. Between the weight, the pallet handling and the mixing, a 24×24 pour is not a bag job. Order ready-mix instead: the slab needs 192 ÷ 27 ≈ 7.1 yd³, so have the plant deliver about 7.5 yd³ to cover waste, grade variation and a small safety margin.

Bags or ready-mix? Tips for a 24×24 pour

• Garage slabs and other big pours call for ready-mix — truck-batched concrete is stronger and more consistent than anything hand-mixed, and at 25,600 lb the bag route stops being an option. Save 80-lb bags for footings, small pads and repairs.
• Put down a proper subbase — for 576 sq ft, excavate, then add and compact about 4 in of gravel or crusher run. Set rebar or welded wire mesh on chairs so the slab is supported under its full footprint and doesn't settle at the edges.
• Plan how the concrete gets from truck to slab — a ready-mix chute reaches only partway across 24 ft. Order a pump truck (or long chute extensions) so you place and finish the pour in time instead of moving wet concrete by wheelbarrow.
• Price the whole job before you pour — material is the smaller half of the budget; see how much a concrete slab costs for installed-cost ballparks in your area.

Pouring a 20×20 ft pad instead of 24×24? The method is identical — area × thickness ÷ 12, then ÷ 0.6 for bags — and we've run the numbers in how many bags of concrete for a 20×20 slab. Either way, run your exact slab through the concrete calculator and confirm the yardage with your ready-mix supplier before the truck rolls.

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