24x40 Concrete Slab, 4 Inches Thick
Poured 4 in thick, a 24 × 40 ft slab covering 960 sq ft needs about 13.04 cubic yards of concrete once 10% is added for waste. For ready-mix, order 13.25 cu yd for the 24x40, about $1,855 – $2,385 delivered. Bagged, the same 24x40 is 587 80 lb or 783 60 lb bags, about $3,915 – $5,481 for the concrete alone.
- Ready-mix order
- 13.25 cu yd
- Ready-mix cost
- $1,855 – $2,385
- 80 lb bags
- 587
- Bag cost
- $3,915 – $5,481
Materials only for a 24x40 at 4 in, from national price ranges as of 2026-09; not a live quote.
What a 24x40 slab holds
At 960 sq ft, a 24x40 is a long garage that parks three cars nose to tail in two rows, or two cars plus a 16 ft workshop, or a pole barn with an RV-length bay.
An RV bay needs height more than floor area, so if a camper is the reason for the 40 ft length, check the door and eave height before the slab is laid out.
A slab this long should be laid out with joints across the 40 ft length about every 10 ft at 4 in thick.
A 4 in 24x40 pour: check first
- If an RV or a loaded trailer parks here, consider 5 to 6 in where the wheels sit.
- Plan a door at each end if you want to drive through with a trailer.
- Arrange a pump or a second chute if the truck cannot reach the far end.
Full plan for a 24x40 slab, 4 in
- Area
- 960 sq ft
- Thickness
- 4 in
- Volume
- 13.04 cu yd
Bagged concrete estimate (DIY)
$4,845 – $6,995
Est. as of 2026-09 — not a live quote
Ready-mix delivered (materials only)
$1,855 – $2,385
Est. as of 2026-09 — not a live quote
For a pour this size, ready-mix delivery is typically more practical than mixing bags by hand.
Shopping list
- Concrete mix (60 lb bags) Or 1,174 × 40 lb, 939 × 50 lb or 587 × 80 lb bags. 783 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 13.25 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 16 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 1,056 sq ft
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Buy bagged concrete
Pick up bagged mix and reinforcement from a hardware store for smaller pours.
View shopping listAssumptions
- Waste allowance: 10% applied to account for over-excavation and spillage.
- Approx. wet weight: 52,800 lb (26.4 tons).
- Prices are national-average retail/delivery ranges as of 2026-09, not live quotes.
Bags or ready-mix for a 24x40 slab, 4 in?
The 24x40 at 4 in needs 2 trucks: 13.25 cu yd at 8 cu yd a load, the low end of what a truck carries, for about $1,855 – $2,385. Ask the supplier to space the trucks so each load goes down before the last one stiffens (a wet edge), line up enough hands to place and finish 960 sq ft at 4 in, and ask about a pump if the truck can't reach every corner of the 24x40. Ready-mix wins for this 24x40 by roughly $2,578 (range midpoints), and nobody has to mix 587 bags by hand.
Is 4 in thick enough for a 24x40 slab?
For a 24x40 garage or shop floor that carries passenger cars, 4 in is common and above the IRC minimum of 3-1/2 in. Go to 5 or 6 in if the 24x40 will hold heavy pickups, an RV, a car lift or a tractor, or sits on soft or clay soil, and check your local code first. At 6 in the same 24x40 takes about 19.56 cu yd.
Control joints for a 24x40 slab at 4 in
Like any slab, a 4 in 24x40 shrinks while it cures; control joints decide where its cracks go. The usual rule (ACI and PCA guidance) puts joints in a 24x40 at 4 in every 8 to 12 ft, 24 to 36 times the thickness, cut 1 in deep (a quarter of the thickness) as soon as the surface takes the saw without raveling, usually within the first day.
On the 24x40 at 4 in, a joint every 10 ft or less means 3 joints across the 40 ft side and 2 joints across the 24 ft side: 12 panels of about 10 × 8 ft and 152 ft of saw cut. The 24x40 is 1.7 times as long as it is wide, and long, narrow slabs crack across their width, so don't skip its cross joints.
How much a 24x40 slab 4 in thick weighs
At roughly 150 lb per cubic foot of wet concrete, a 24x40 at 4 in puts about 52,800 lb (26.4 tons) on the ground. As bags, the 24x40 is 587 80 lb bags, 46,960 lb in all: about 32 trips in a pickup carrying 1,500 lb a load. Nobody hauls 46,960 lb of bags for a 24x40 in a pickup; it comes by ready-mix truck or as pallets on a delivery truck.
The 24x40 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 24x40 at 4 in; costs are for the concrete only.
| Slab | Cu yd | 60 lb bags | 80 lb bags | Ready-mix order | Bags cost | Ready-mix cost |
|---|---|---|---|---|---|---|
| 30x30 slab, 4 in | 12.22 | 734 | 550 | 12.25 cu yd | $3,670 – $5,138 | $1,715 – $2,205 |
| 24x40 slab, 4 in (this page) | 13.04 | 783 | 587 | 13.25 cu yd | $3,915 – $5,481 | $1,855 – $2,385 |
| 30x40 slab, 4 in | 16.3 | 978 | 734 | 16.5 cu yd | $4,890 – $6,846 | $2,310 – $2,970 |
Questions about a 24x40 slab, 4 in
How many bags of concrete for a 24x40 slab 4 inches thick?
Plan on 352 cubic feet for the 24x40, which is 587 80 lb bags, 783 60 lb bags, 939 50 lb or 1,174 40 lb bags once 10% waste is in.
How many yards of concrete for a 24x40 slab 4 inches thick?
13.04 cubic yards with waste (11.85 without) for a 24x40 at 4 in. Round the 24x40 order to 13.25 cu yd: plants batch in quarter yards and most won't send less than a yard.
How much does a 24x40 concrete slab 4 inches thick cost?
Concrete alone for the 24x40 runs about $1,855 – $2,385 for 13.25 cu yd of ready-mix delivered, or $3,915 – $5,481 for 783 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 24x40 plan comes to $4,845 – $6,995. Labor, forms and finishing for a 24x40 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 24x40 concrete slab 4 inches thick weigh?
About 52,800 lb (26.4 tons) of wet concrete for the 24x40, at 150 lb per cubic foot. The 587 80 lb bags for a 24x40 weigh 46,960 lb: about 32 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 24x40 slab 4 inches thick?
On a 24x40 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. On the 24x40 at 4 in, a joint every 10 ft or less means 3 joints across the 40 ft side and 2 joints across the 24 ft side: 12 panels of about 10 × 8 ft and 152 ft of saw cut.
Limitations
The 24x40 figures at 4 in are material estimates and typical price ranges, not a quote or a structural design. Confirm that 4 in, the reinforcement and the joint layout suit your soil, loads and local code for a 24x40 slab with a qualified professional.