How much does a concrete slab cost? (10x10 to 24x30)
A 10 x 10 ft slab 4 inches thick takes 1.36 cubic yards with 10% waste and costs about $300 in ready-mix delivered at $150 a yard with the short-load fee, or $434 in 62 bags of 80 lb. A 20 x 20 ft slab is 5.43 yards and about $825. That is the concrete alone: forms, mesh, the gravel base and the crew are on top, and the tables show where bags stop making sense.
Open the concrete cost calculator
Slab cost at 4 inches
Each row is the concrete with 10% waste, priced two ways from the concrete cost calculator's starting figures: a ready-mix delivery at $150 per yard in quarter-yard steps with a $75 short-load fee under 5 yards, and 80 lb bags at $7. The last column is the cheaper of the two per square foot.
| Slab | Cubic yards | Ready-mix delivered | 80 lb bags | Bags cost | Per sq ft |
|---|---|---|---|---|---|
| 10 x 10 ft | 1.36 | $300 | 62 | $434 | $3.00 |
| 10 x 12 ft | 1.63 | $338 | 74 | $518 | $2.81 |
| 12 x 12 ft | 1.96 | $375 | 88 | $616 | $2.60 |
| 12 x 16 ft | 2.61 | $488 | 118 | $826 | $2.54 |
| 16 x 16 ft | 3.48 | $600 | 157 | $1,099 | $2.34 |
| 20 x 20 ft | 5.43 | $825 | 245 | $1,715 | $2.06 |
| 24 x 24 ft | 7.82 | $1,200 | 352 | $2,464 | $2.08 |
| 24 x 30 ft | 9.78 | $1,500 | 440 | $3,080 | $2.08 |
Slab cost at 6 inches
Garages, workshops and anything a truck parks on are poured thicker. Half again the volume means half again the concrete cost, and the larger slabs clear the minimum load, so the fee drops out.
| Slab | Cubic yards | Ready-mix delivered | 80 lb bags | Bags cost | Per sq ft |
|---|---|---|---|---|---|
| 10 x 10 ft | 2.04 | $412 | 92 | $644 | $4.12 |
| 10 x 12 ft | 2.44 | $450 | 110 | $770 | $3.75 |
| 12 x 12 ft | 2.93 | $525 | 132 | $924 | $3.65 |
| 12 x 16 ft | 3.91 | $675 | 176 | $1,232 | $3.52 |
| 16 x 16 ft | 5.21 | $788 | 235 | $1,645 | $3.08 |
| 20 x 20 ft | 8.15 | $1,237 | 367 | $2,569 | $3.09 |
| 24 x 24 ft | 11.73 | $1,763 | 528 | $3,696 | $3.06 |
| 24 x 30 ft | 14.67 | $2,213 | 660 | $4,620 | $3.07 |
Truck or bags?
Bagged mix costs about twice as much per yard as a delivered truck, so at these prices the truck is cheaper from roughly 0.5 cubic yards, which is smaller than every slab in the tables. A 10 x 10 slab still gets bagged all the time, for reasons other than price: no truck access, no crew for the day, or a plant that will not send a truck for one yard. By 24 x 24 ft the bag count (352 bags of 80 lb) is a pallet and a half mixed by hand, which no one does for a slab that must be poured in one go. The yard of concrete guide shows the crossover load by load.
From concrete cost to installed cost
Contractors quote a slab per square foot installed, and that number is several times the concrete alone. It covers excavation, the gravel base, forms, reinforcement, the pour, finishing, joints and cleanup, plus their labour and margin. Use the tables here to check the material line of a quote and to see what a thicker slab really adds; the Pro quote builder adds labour, extras, margin and tax on top of the material list if you are the one quoting.
Before you order
- Measure the formed size, not the nominal one, and keep the 10% waste: ground is never flat and a slab that runs short mid-pour needs a second short load with a second fee.
- Work out the base separately with the gravel calculator; 4 inches of compacted crushed stone is usual under a slab.
- For the bag counts by size and thickness see concrete for a 12x12 slab and bags for a 10x10 slab.
Frequently asked questions
- How much does a 10x10 concrete slab cost?
- About $300 of concrete at 4 inches thick: 1.36 cubic yards delivered at $150 a yard plus a $75 short-load fee, or 62 bags of 80 lb for $434. The truck is cheaper even with the short-load fee; bags are the choice only when a truck cannot reach the forms. Add the sub-base, forms, mesh and finishing for the installed price.
- How much does a 12x12 concrete slab cost?
- 1.96 cubic yards at 4 inches, about $375 delivered including the short-load fee, or 88 bags of 80 lb at $616. The truck is cheaper even with the short-load fee; bags are the choice only when a truck cannot reach the forms.
- How much does a 20x20 concrete slab cost?
- 5.43 cubic yards at 4 inches, about $825 delivered, with the short-load fee no longer charged because the order reaches the minimum load. At 6 inches for a garage or a workshop it is 8.15 yards and about $1,237. Bags would be 245, which is not a practical way to pour a slab this size.
- How much is a concrete slab per square foot in material?
- Between about $2.06 and $3.00 per square foot at 4 inches with the 2026 default prices, the small slabs at the top of the range because the short-load fee is spread over less area. Six inches thick adds half again. Installed prices quoted by contractors are several times higher because they include the base, forms, reinforcement, finishing and labour.
- Should a slab be 4 or 6 inches thick?
- 4 inches is the standard for patios, sheds and walkways with foot traffic and light loads. Go to 5 or 6 inches for a garage, a driveway used by trucks, or a workshop with heavy machines, and add rebar or wire mesh; your local code may set the minimum for a garage floor.
- What else is on the bill besides the concrete?
- The compacted gravel base (usually 4 inches), forms and stakes, a vapour barrier if the slab is inside, wire mesh or rebar, the pour and finish, saw cuts for control joints, curing compound or sealer, and removal of whatever was there before. Get those as separate lines on a quote so you can compare contractors.
More guides
- How much is a yard of concrete? (delivered, 2026)
Ready-mix runs about 125 to 175 per cubic yard in the US, 2026, plus a short-load fee under 3 to 5 yards. What 1 to 10 yards cost delivered, and the same volume in bags.
- How much does a concrete driveway cost? (concrete only)
Ready-mix cost for single and double driveways from 10x20 to 24x40 ft at 4, 5 and 6 inches, cost per square foot, why bags do not work, and what else is on the bill.
- How much does a cinder block garage cost? (blocks, mortar, grout and slab for 1, 2 and 3 car)
Blocks, mortar and grout for 1 to 3 car block garages, 12x20 to 36x24 ft, 8 ft walls, doors and windows taken off, plus the 4 in slab, at 2026 prices.
- How much does a ton of gravel cover? (at 2, 3 and 4 inches, by stone)
A ton of 3/4 in crushed stone is 0.79 cubic yards: about 85 sq ft at 3 in, 128 at 2 in, 64 at 4 in. Coverage by stone, tons for 100 to 1,000 sq ft, price.
Last updated 2026-09-14. Figures are planning estimates from typical product data: check the yield, size or coverage printed on what you buy and round up.