How many yards of concrete for a 24×24 slab?
A 24 × 24 ft slab 4 inches thick is 7.11 cubic yards of concrete, or 7.82 cubic yards with 10% extra. In 80 lb bags it would be 352 bags, so this is a ready-mix pour.
How to work it out
- 24 ft × 24 ft = 576 sq ft
- 576 sq ft × 4 in ÷ 12 = 192 cu ft ÷ 27 = 7.11 cu yd
- + 10% extra = 7.82 cu yd = 211 cu ft
- 211 cu ft ÷ 0.6 cu ft per 80 lb bag = 352 bags
A 24 × 24 detached garage is one of the most common slabs people plan themselves, and the searches come in two forms: how many yards to order, and (hopefully just out of curiosity) how many bags it would take.
Adjust for your project
More options: Extra · Price
- Or bags of mix (incl. extra)
- 352 bags · 80 lb bag
- Concrete before the extra
- 7.11 cu yd (192 cu ft)
- Slab area
- 576 sq ft
- Weight of the concrete (≈ 145 lb/cu ft)
- 27,840 lb (14 tons)
- 352 bags is a lot of mixing. Compare a ready-mix delivery (ask about minimum loads and short-load fees) with the bags vs ready-mix calculator.
- Total to buy counts this as ready-mix. Switch “How will you buy it?” to bags if you are mixing it yourself.
- Plan control joints about 1 in deep every 6–8 ft (Quikrete’s guidance) so shrinkage cracks follow your lines.
24×24 slab by thickness (10% extra included)
| Thickness | Concrete to order | Concrete before the extra | Weight of the concrete (≈ 145 lb/cu ft) |
|---|---|---|---|
| 4 in | 7.82 cu yd | 7.11 cu yd | 27,840 lb |
| 5 in | 9.78 cu yd | 8.89 cu yd | 34,800 lb |
| 6 in | 11.7 cu yd | 10.7 cu yd | 41,760 lb |
Yards for a 24×24 garage floor
At 4 in, the floor alone is 7.11 yards; with a 10% allowance, 7.82. A garage floor is a code matter, though: the thickness, any reinforcement, a thickened edge or separate perimeter footings and the base under it all come from your plans and local building department. Run their numbers through the calculator — at 5 in the floor is 8.89 yards before extra, and at 6 in it is 10.67.
If the plans call for a monolithic slab with a thickened edge, that edge adds a lot. A turned-down edge 12 in wide and 8 in deeper than the slab, all the way round a 24 × 24, adds about 2.3 cubic yards on its own. Add it with the footing volume calculator using the perimeter (96 ft) as the length.
One truck or two
NRMCA puts the capacity of truck mixers at 8 to 12 cubic yards, and the real figure depends on the truck and local road weight limits. An order near 8 yards usually fits one truck, while 11–12 yards for a 6 in floor with a thickened edge may need two. Ask the plant to space the second truck so it arrives as the first is emptying. The ready-mix vs bags calculator has the load math.
A smaller pad of the same shape is on how much concrete for a 20×20 slab; for a shop-sized building, see how much concrete for a 30×40 slab.
Different size? Use the full Concrete Calculator.
What you’ll need
- Bull float with handleMid-range price
Smooths and levels a slab you can’t reach across, right after screeding. Rent or buy one for anything wider than about 6 ft.
See options on Amazon (opens in a new tab) - Rebar chairsBudget price
Hold rebar or mesh off the ground so it ends up inside the concrete, not under it. Match the chair height to where your plans place the steel.
See options on Amazon (opens in a new tab) - Concrete finishing broomMid-range price
Drags a non-slip texture into a walkway or patio once the surface has stiffened.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many yards of concrete for a 24×24 slab 6 inches thick?
10.7 cubic yards before extra, 11.7 cubic yards with 10%.
How many yards of concrete for a 24×24 slab 5 inches thick?
8.89 cubic yards, or 9.78 cubic yards with 10% extra.
How many bags of concrete for a 24×24 slab?
352 bags of 80 lb at 4 inches with 10% extra, roughly 27,840 pounds of wet concrete. Order ready-mix.
Other common sizes
- How much concrete for a 10×10 slab — 1.36 cu yd with 10% extra (62 bags of 80 lb)
- How much concrete for a 12×12 slab — 1.96 cu yd with 10% extra (order 2 yd)
- How much concrete for a 20×20 slab — 5.43 cu yd with 10% extra at 4 in
- How much concrete for a 30×40 slab — 16.3 cu yd with 10% extra at 4 in
- How many bags of concrete for a 4×4 slab — 10 bags of 80 lb (14 of 60 lb), 4 in thick
- How many bags of concrete for an 8×8 slab — 40 bags of 80 lb, 4 in thick
- How much concrete for a 10×12 shed — 1.63 cu yd with 10% extra; about 2 cu yd with a thickened edge
Sources
- Quikrete Concrete Mix (No. 1101) data sheet (opens in a new tab) — Yields: 40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60, 90 lb ≈ 0.675 cu ft; unit weight ≈ 140 lb/cu ft; for pours 2 in thick or more; 6–9 pints of water per 80 lb bag; control joints every 6–8 ft; cure 5 days at 70 °F or above, 7 days at 50–70 °F; protect from freezing for 48 hours.
- NRMCA Concrete in Practice 31 — Ordering Ready Mixed Concrete (opens in a new tab) — Truck mixers carry 8 to 12 cubic yards (about 6 to 9 m³); order 4–10% more than the plan estimate; a loaded truck weighs about 80,000 lb; fresh concrete can cause severe chemical burns.
- NRMCA Concrete in Practice 2 — Scaling Concrete Surfaces (opens in a new tab) — Order air-entrained concrete (about 6% air) for exterior slabs exposed to freezing and de-icers; avoid de-icing chemicals in the first winter.
- Iowa DOT Instructional Memorandum 340 — Weight per cubic foot, yield and air content of concrete (opens in a new tab) — Normal-weight concrete is typically 140–150 lb per cu ft at 5 to 8 percent air.
- OSHA 3351 — Preventing Skin Problems from Working with Portland Cement (opens in a new tab) — Wet portland cement can cause caustic burns that may not hurt at first and in severe cases reach the bone.
- NIST Handbook 44, Appendix C — General Tables of Units of Measurement (opens in a new tab) — 1 cubic yard = 27 cubic feet; 1 cubic foot = 1,728 cubic inches.