12x30 Concrete Slab, 4 Inches Thick
A 12 × 30 ft slab (360 sq ft) at 4 in thick takes about 4.89 cubic yards of concrete, with 10% extra for waste. For ready-mix, order 5 cu yd for the 12x30, about $760 – $1,010 delivered, short-load fee included. Bagged, the same 12x30 is 220 80 lb or 294 60 lb bags, about $1,470 – $2,058 for the concrete alone.
- Ready-mix order
- 5 cu yd
- Ready-mix cost
- $760 – $1,010
- 80 lb bags
- 220
- Bag cost
- $1,470 – $2,058
The 12x30 (4 in) prices are national material ranges as of 2026-09, not a quote from a supplier.
The 12x30 single-car driveway
Twelve feet is a comfortable width for a single driveway, and 30 ft parks one vehicle fully off the street with room to walk around it.
Four inches is the usual thickness for a driveway that carries passenger cars, with 5 to 6 in where heavy trucks, a camper or delivery vehicles will use it.
Driveways crack where they bend, so the control joints matter more here than on a patio: across the width about every 10 ft at 4 in.
A 4 in 12x30 pour: check first
- Ask the town about the apron and curb cut at the street; it often has its own permit and thickness rule.
- Slope the driveway so water runs away from the garage and the house.
- Compact the base well at the street end, where trucks turning in put the most load on the edge.
Full plan for a 12x30 slab, 4 in
- Area
- 360 sq ft
- Thickness
- 4 in
- Volume
- 4.89 cu yd
Bagged concrete estimate (DIY)
$1,819 – $2,626
Est. as of 2026-09 — not a live quote
Ready-mix delivered, incl. short-load fee (materials only)
$760 – $1,010
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 440 × 40 lb, 352 × 50 lb or 220 × 80 lb bags. 294 bags
- Ready-mix concrete Alternative to bagged mix; most suppliers have a 1 cu yd order minimum. 5 cu yd
- Compactable gravel sub-base 4 in compacted base beneath the slab. 6 tons
- 6x6 welded wire mesh Reinforcement for crack control; not a substitute for engineered rebar on structural slabs. 396 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: 19,800 lb (9.9 tons).
- Prices are national-average retail/delivery ranges as of 2026-09, not live quotes.
- Ready-mix orders under 10 cu yd usually carry a short-load fee; the ready-mix range includes a flat $60-$110. Some suppliers charge per yard instead, so ask for the full fee schedule.
Bags or ready-mix for a 12x30 slab, 4 in?
4.89 cu yd for the 12x30 fits on one ready-mix truck (they carry about 8 to 10 cu yd). In bags the 12x30 would be 220 80 lb bags weighing 17,600 lb, so ready-mix is the practical choice. Under 10 cu yd most suppliers add a short-load fee, and the $760 – $1,010 range for the 12x30 includes one. Ready-mix wins for this 12x30 by roughly $879 (range midpoints), and nobody has to mix 220 bags by hand.
Is 4 in thick enough for a 12x30 slab?
A 12x30 driveway at 4 in suits passenger cars on a well-compacted base. Heavy trucks, a camper or regular deliveries call for 5 to 6 in, and your town may set its own rule for the apron; at 6 in the 12x30 takes about 7.33 cu yd.
Control joints for a 12x30 slab at 4 in
Like any slab, a 4 in 12x30 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 12x30 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 12x30 at 4 in, a joint every 10 ft or less means 3 joints across the 30 ft side and 1 joint across the 12 ft side: 8 panels of about 7.5 × 6 ft and 66 ft of saw cut. For the 12x30 that's more joints than the spacing alone calls for, so that no panel is more than 1.5 times as long as it is wide. The 12x30 is 2.5 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 12x30 slab 4 in thick weighs
Wet concrete weighs about 150 lb per cubic foot, so the 12x30 pour is about 19,800 lb (9.9 tons). As bags, the 12x30 is 220 80 lb bags, 17,600 lb in all: about 12 trips in a pickup carrying 1,500 lb a load. Nobody hauls 17,600 lb of bags for a 12x30 in a pickup; it comes by ready-mix truck or as pallets on a delivery truck.
The 12x30 at 4 in against nearby sizes
Every row uses the same 10% waste and prices as the 12x30 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 |
|---|---|---|---|---|---|---|
| 16x20 slab, 4 in | 4.35 | 261 | 196 | 4.5 cu yd | $1,305 – $1,827 | $690 – $920 |
| 12x30 slab, 4 in (this page) | 4.89 | 294 | 220 | 5 cu yd | $1,470 – $2,058 | $760 – $1,010 |
| 20x20 slab, 4 in | 5.43 | 326 | 245 | 5.5 cu yd | $1,630 – $2,282 | $830 – $1,100 |
Questions about a 12x30 slab, 4 in
How many bags of concrete for a 12x30 slab 4 inches thick?
Plan on 132 cubic feet for the 12x30, which is 220 80 lb bags, 294 60 lb bags, 352 50 lb or 440 40 lb bags once 10% waste is in.
How many yards of concrete for a 12x30 slab 4 inches thick?
4.89 cubic yards with waste (4.44 without) for a 12x30 at 4 in. Round the 12x30 order to 5 cu yd: plants batch in quarter yards and most won't send less than a yard.
How much does a 12x30 concrete slab 4 inches thick cost?
Concrete alone for the 12x30 runs about $760 – $1,010 for 5 cu yd of ready-mix delivered, short-load fee included, or $1,470 – $2,058 for 294 60 lb bags. Add a 4 in gravel base and wire mesh and the bagged 12x30 plan comes to $1,819 – $2,626. Labor, forms and finishing for a 12x30 at 4 in come on top of these national ranges (as of 2026-09), which are not quotes.
How much does a 12x30 concrete slab 4 inches thick weigh?
About 19,800 lb (9.9 tons) of wet concrete for the 12x30, at 150 lb per cubic foot. The 220 80 lb bags for a 12x30 weigh 17,600 lb: about 12 trips in a pickup carrying 1,500 lb a load.
Where do control joints go on a 12x30 slab 4 inches thick?
On a 12x30 at 4 in, every 8 to 12 ft (24 to 36 times the thickness), sawn 1 in deep. On the 12x30 at 4 in, a joint every 10 ft or less means 3 joints across the 30 ft side and 1 joint across the 12 ft side: 8 panels of about 7.5 × 6 ft and 66 ft of saw cut.
Limitations
The 12x30 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 12x30 slab with a qualified professional.