24x30 Concrete Slab, 4 Inches Thick
A 24 × 30 ft slab (720 sq ft) at 4 in thick takes about 9.78 cubic yards of concrete, with 10% extra for waste. For ready-mix, order 10 cu yd for the 24x30, about $1,400 – $1,800 delivered. Bagged, the same 24x30 is 440 80 lb or 587 60 lb bags, about $2,935 – $4,109 for the concrete alone.
- Ready-mix order
- 10 cu yd
- Ready-mix cost
- $1,400 – $1,800
- 80 lb bags
- 440
- Bag cost
- $2,935 – $4,109
The 24x30 (4 in) prices are national material ranges as of 2026-09, not a quote from a supplier.
Planning a 24x30 slab
A 24x30 slab is a two-car garage with a 6 ft deep workshop or storage zone along the back, or a pole barn for a pickup, a tractor and implements.
Its 720 sq ft is a size many garage-kit sellers stock, and it is long enough for a workbench, a tool chest and a parked car on each side.
The pour is a little over one ready-mix truckload at 4 in, so ask the supplier how the second, smaller load will be timed.
A 4 in 24x30 pour: check first
- Ask the supplier to time the second truck so the first load is still workable when it arrives.
- Plan the outlets and any compressor line before the pour if they will run under the floor.
- Keep the shop end flat for rolling tool chests.
Full plan for a 24x30 slab, 4 in
- Area
- 720 sq ft
- Thickness
- 4 in
- Volume
- 9.78 cu yd
Bagged concrete estimate (DIY)
$3,632 – $5,244
Est. as of 2026-09 — not a live quote
Ready-mix delivered (materials only)
$1,400 – $1,800
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 880 × 40 lb, 704 × 50 lb or 440 × 80 lb bags. 587 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 10 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 12 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 792 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: 39,600 lb (19.8 tons).
- Prices are national-average retail/delivery ranges as of 2026-09, not live quotes.
Bags or ready-mix for a 24x30 slab, 4 in?
10 cu yd for the 24x30 is 2 truckloads at 8 cu yd each (the conservative end of the 8 to 10 a truck carries), about $1,400 – $1,800. 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 720 sq ft at 4 in, and ask about a pump if the truck can't reach every corner of the 24x30. Ready-mix wins for this 24x30 by roughly $1,922 (range midpoints), and nobody has to mix 440 bags by hand.
Is 4 in thick enough for a 24x30 slab?
Many residential garage floors the size of this 24x30 are poured 4 in thick, which clears the IRC minimum of 3-1/2 in for cars and light trucks. Go to 5 or 6 in if the 24x30 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 24x30 takes about 14.67 cu yd.
Control joints for a 24x30 slab at 4 in
Like any slab, a 4 in 24x30 shrinks while it cures; control joints decide where its cracks go. ACI and PCA guidance spaces joints 24 to 36 times the thickness, which for this 24x30 at 4 in is every 8 to 12 ft, sawn 1 in deep (a quarter of the slab) once the surface holds up to the blade, usually within a day.
On the 24x30 at 4 in, a joint every 10 ft or less means 2 joints across the 30 ft side and 2 joints across the 24 ft side: 9 panels of about 10 × 8 ft and 108 ft of saw cut.
How much a 24x30 slab 4 in thick weighs
Wet concrete weighs about 150 lb per cubic foot, so the 24x30 pour is about 39,600 lb (19.8 tons). As bags, the 24x30 is 440 80 lb bags, 35,200 lb in all: about 24 trips in a pickup carrying 1,500 lb a load. Nobody hauls 35,200 lb of bags for a 24x30 in a pickup; it comes by ready-mix truck or as pallets on a delivery truck.
The 24x30 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 24x30 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 |
|---|---|---|---|---|---|---|
| 20x30 slab, 4 in | 8.15 | 489 | 367 | 8.25 cu yd | $2,445 – $3,423 | $1,215 – $1,595 |
| 24x30 slab, 4 in (this page) | 9.78 | 587 | 440 | 10 cu yd | $2,935 – $4,109 | $1,400 – $1,800 |
| 20x40 slab, 4 in | 10.86 | 652 | 489 | 11 cu yd | $3,260 – $4,564 | $1,540 – $1,980 |
Questions about a 24x30 slab, 4 in
How many bags of concrete for a 24x30 slab 4 inches thick?
Plan on 264 cubic feet for the 24x30, which is 440 80 lb bags, 587 60 lb bags, 704 50 lb or 880 40 lb bags once 10% waste is in.
How many yards of concrete for a 24x30 slab 4 inches thick?
9.78 cubic yards with waste (8.89 without) for a 24x30 at 4 in. Round the 24x30 order to 10 cu yd: plants batch in quarter yards and most won't send less than a yard.
How much does a 24x30 concrete slab 4 inches thick cost?
Concrete alone for the 24x30 runs about $1,400 – $1,800 for 10 cu yd of ready-mix delivered, or $2,935 – $4,109 for 587 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 24x30 plan comes to $3,632 – $5,244. Labor, forms and finishing for a 24x30 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 24x30 concrete slab 4 inches thick weigh?
About 39,600 lb (19.8 tons) of wet concrete for the 24x30, at 150 lb per cubic foot. The 440 80 lb bags for a 24x30 weigh 35,200 lb: about 24 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 24x30 slab 4 inches thick?
On a 24x30 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. On the 24x30 at 4 in, a joint every 10 ft or less means 2 joints across the 30 ft side and 2 joints across the 24 ft side: 9 panels of about 10 × 8 ft and 108 ft of saw cut.
Limitations
The 24x30 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 24x30 slab with a qualified professional.