How Many Yards of Concrete for a 24 x 24 Slab?
A 24 by 24 foot slab (576 square feet) poured 4 inches thick needs 7.11 cubic yards of concrete. With 10% extra, order about 8 cubic yards. At 5 inches order about 10 yards and at 6 inches about 12 yards.
Concrete needed for a 24 x 24 slab
A 24 × 24 slab is the standard footprint of a two-car garage. The slab is 576 square feet. Ready-mix is sold by the cubic yard, so multiply the area by the thickness in feet and divide by 27.
At 4 inches thick: 576 × 0.3333 = 192.0 cubic feet, and 192.0 ÷ 27 = 7.11 cubic yards. Add 10% and the number to order is 7.82, which most suppliers will round to 8 yards.
24x24 slab concrete chart
| Thickness | Exact yards | With 10% extra | Round to order | Approx. weight |
|---|---|---|---|---|
| 4 in | 7.11 | 7.82 | 8 | 15.6 tons |
| 5 in | 8.89 | 9.78 | 10 | 19.6 tons |
| 6 in | 10.67 | 11.73 | 12 | 23.5 tons |
Fresh concrete weighs about 2 tons per cubic yard (roughly 4,000 lb), which matters for truck access and for any driveway, lawn or sewer line the truck must cross.
Thickness for this slab
Garage floors are usually 4 to 6 inches thick, with a thicker or reinforced edge; ask your building department for the required spec. Each extra inch of thickness adds about 1.78 cubic yards to this slab, so a small change in the spec moves the order noticeably.
Ordering from a ready-mix plant
- Most plants sell in half-yard steps above a minimum load, and charge a short-load fee for small orders, so ask for the total delivered price.
- Tell the dispatcher the slab size, thickness and the exposure (freeze-thaw, de-icing salt) so they quote a suitable mix.
- Have forms, base and finishing tools ready before the truck arrives; discharge time is limited.
- If you are close to a round number, order the larger one. Running short mid-pour leaves a cold joint.
Check other sizes with the concrete calculator, see the cost with the concrete cost calculator, or measure an odd shape with the square footage calculator.
Common mistakes
- Ordering the exact volume and running short on a high spot.
- No clear path for the truck, or no plan for washing out the chute.
- Pouring in very hot, cold or rainy weather without a plan.
- Not asking about the mix design when the slab will see freezing and salt.
Other sizes
How Many Yards of Concrete for a 20x20 Slab · How Many Yards of Concrete for a 10x20 Slab
Calculators for this guide
Frequently asked questions
How many yards of concrete do I need for a 24x24 slab at 4 inches?
7.11 cubic yards exact, and about 8 yards to order with 10% extra.
How many yards for a 24x24 slab at 6 inches?
10.67 cubic yards exact, or about 12 to order.
How many bags of concrete are in a yard?
About 45 bags of 80 lb mix, 60 bags of 60 lb, or 90 bags of 40 lb make one cubic yard.
How much does a concrete truck hold?
A standard ready-mix truck carries about 8 to 10 cubic yards, so this slab fits in one load.
What is a typical slab thickness?
Four inches is common for patios and walks; garages and driveways are often 5 to 6 inches. Follow your local code.
Sources and further reading
- Concrete driveways and slabs — American Cement Association
- National Ready Mixed Concrete Association — NRMCA: ready-mix industry resources
- NIST Special Publication 811: conversion factors — National Institute of Standards and Technology
More guides
Estimates only. Always confirm quantities with your supplier or a qualified contractor before ordering, and add extra for waste and site conditions.