How Much Concrete for a 24x24 Slab (2026): Yards, Bags, and Cost

24 × 24 slab by thickness

Every figure includes 10% waste. Bag counts use the manufacturers' stated yields (0.6 cu ft per 80 lb bag, 0.45 per 60 lb).

Thickness	Cubic yards	80 lb bags	60 lb bags	Bags cost	Ready-mix cost
4 in	7.82	353	470	$2,118 to $2,824	$1,017 to $1,486
5 in	9.78	440	587	$2,640 to $3,520	$1,271 to $1,858
6 in	11.73	528	704	$3,168 to $4,224	$1,525 to $2,229
8 in	15.64	705	939	$4,230 to $5,640	$2,034 to $2,972

Garage floors this size almost always need a permit and an inspection of the forms and reinforcement before the pour. Budget a week for that.

Building a 24 × 24 slab

A 24 × 24 two-car garage floor is inspected work in most towns: the forms, gravel, vapor barrier, and rebar get looked at before the truck comes. Six inches, #4 rebar on an 18-inch grid, thickened edges where the walls sit, and the floor sloped 1/8 inch per foot toward the door so a wet car drains out instead of pooling. Cut joints at 12 feet each way for four 12 × 12 panels, 1.5 inches deep on a 6-inch slab. Set the anchor bolts for the wall plates in the wet concrete on the inspector's layout.

Pour day at this size

Around 11.7 yards at 6 inches, which is two trucks timed 30 minutes apart so the first load doesn't set before the second arrives. Four people, a power screed or a long straightedge, and a broom finish. This is the size where most owners price the finishing crew separately: forms and rebar yourself, then pay a finisher for pour day.

Joint spacing and depth follow ACI 302.1R (joints every 24 to 36 times the slab thickness, cut one quarter deep); anchor bolt spacing follows IRC R403.1.6; load figures come from manufacturers' published weights. Local code wins where it differs.

Having it poured instead

Contractors charge about $6 to $12 per square footfor a finished 4-inch slab in 2026, which puts a 24 × 24 slab at$3,456 to $6,912 installed. That covers forming, gravel base, pour, and finish; thicker slabs, reinforcement, and site prep on sloped or hard-to-reach ground push it toward the top of the range.

How we get these numbers

Volume is length × width × thickness in cubic feet, divided by 27, plus 10% waste. Bag yields come from the manufacturers' technical data sheets. Ready-mix runs $130 to $190per yard delivered, with a $50 to $150short-load fee under 5 yards at most plants. Prices refreshed at least twice a year (last: September 2026). Sources:

Frequently asked questions

How many bags of concrete for a 24x24 slab?

At 6 inches thick, 528 bags of 80 lb mix or 704 bags of 60 lb mix, including 10% extra for waste. That is 11.73 cubic yards of concrete.

How much does a 24x24 concrete slab cost?

Poured by a contractor, about $3,456 to $6,912 at 2026 rates of $6 to $12 per square foot for a 4-inch slab, including forming, pouring, and finishing. Doing it yourself, the concrete alone is $3,168 to $4,224 in bags or $1,525 to $2,229 delivered by truck, plus forms, gravel, and reinforcement.

How thick should a 24x24 slab be?

6 inches for a two-car garage floor. Go to 5 or 6 inches if vehicles will park on it, and use wire mesh or rebar in any slab that carries a load.

Do I need a permit for a 24 × 24 garage slab?

Almost always, because it's a building foundation, not a patio. Expect a form and reinforcement inspection before the pour and a final after. Budget a week for the inspection schedule; the concrete itself is one day.

How many trucks for a 24 × 24 slab at 6 inches?

Two. A standard mixer carries 8 to 10 yards and this slab needs 11.7 with waste. Schedule them 30 minutes apart and have the crew ready before the first one backs in.

Other common slab sizes

10 × 10 slab (a shed base, a small patio, or a hot tub pad)
12 × 12 slab (a patio, a larger shed, or a carport pad)
16 × 12 slab (a standard backyard patio)
20 × 16 slab (a large patio or a workshop floor)
20 × 20 slab (a one-car garage floor or a driveway apron)

How much concrete for a 24 × 24 slab