Concrete Slab Cost Calculator: Price per Square Foot and Size
A poured concrete slab costs $6.50 to $10.50 per square foot installed (national range), so a 20×20 ft slab runs about $2,600–$4,200.
Advanced options: waste, prices
NRMCA advises ordering 4 to 10 percent over the estimate.
Concrete needed (with 10% extra)
1.96 yd³
1.50 m³ · 48 ft³ before extra
Slab: 12 ft × 12 ft × 4 in. Over about 1 yd³: order ready-mix.
Premix bags
- 80 lb88
- 60 lb118
- 50 lb141
- 40 lb176
- Ready-mix cost
- $313
- Weight
- 7,200 lb
Full breakdown
| Volume before extra | 1.78 yd³ · 1.36 m³ |
|---|---|
| With 10% extra | 1.96 yd³ |
| Weight (150 lb/ft³) | 7,200 lb · 3.60 tons |
| Pallets of 40 lb (80 bags each) | 3 |
| Pallets of 60 lb (56 bags each) | 3 |
| Pallets of 80 lb (42 bags each) | 3 |
| Truckloads at 12 yd³ | 1 |
| Truckloads at 8 yd³ | 1 |
Bag counts round up, as Quikrete's own calculator does. Cost uses your prices; delivery and short-load fees are extra.
Key takeaways
- Installed slabs: $6.50–10.50 per sq ft (Concrete Network).
- Concrete alone: about $2.17–2.65 per sq ft at 4 in.
- 20×20 slab: about $2,600–4,200 installed.
- Thicker slabs cost more concrete: 6 in = +50%.
How Much Does a Concrete Slab Cost?
A concrete slab costs $6.50 to $10.50 per square foot installed, according to Concrete Network's national range, and the concrete alone is $160 to $195 per cubic yard. A 20×20 ft slab at 4 in costs $2,600–$4,200 installed, of which $869–$1,059 is concrete.
Concrete Slab Cost per Square Foot
A 4 in slab uses 0.0136 yd³ of concrete per square foot with 10% extra, so the material costs about $2.17 to $2.65 per square foot at $160 to $195 per yard; the installed price adds labor, forms and finishing.
Concrete Slab Cost by Size
Concrete slab cost for the sizes people ask about most, at 4 in thick:
| Slab (4 in) | Sq ft | yd³ with 10% | Concrete only | Installed |
|---|---|---|---|---|
| 10×10 ft | 100 | 1.36 | $217–$265 | $650–$1,050 |
| 12×12 ft | 144 | 1.96 | $313–$381 | $936–$1,512 |
| 12×16 ft | 192 | 2.61 | $417–$508 | $1,248–$2,016 |
| 12×20 ft | 240 | 3.26 | $521–$636 | $1,560–$2,520 |
| 14×20 ft | 280 | 3.80 | $608–$741 | $1,820–$2,940 |
| 15×30 ft | 450 | 6.11 | $978–$1,192 | $2,925–$4,725 |
| 20×20 ft | 400 | 5.43 | $869–$1,059 | $2,600–$4,200 |
| 20×30 ft | 600 | 8.15 | $1,304–$1,589 | $3,900–$6,300 |
| 20×40 ft | 800 | 10.86 | $1,738–$2,119 | $5,200–$8,400 |
| 20×60 ft | 1200 | 16.30 | $2,607–$3,178 | $7,800–$12,600 |
| 24×24 ft | 576 | 7.82 | $1,252–$1,525 | $3,744–$6,048 |
| 30×30 ft | 900 | 12.22 | $1,956–$2,383 | $5,850–$9,450 |
| 30×40 ft | 1200 | 16.30 | $2,607–$3,178 | $7,800–$12,600 |
| 40×60 ft | 2400 | 32.59 | $5,215–$6,356 | $15,600–$25,200 |
Slab Cost for a Shed, Garage, Patio or House
| Use | Example size | Concrete only | Installed |
|---|---|---|---|
| Shed | 10×12 ft | $261–$318 | $780–$1,260 |
| Patio | 12×16 ft | $417–$508 | $1,248–$2,016 |
| Two-car garage | 24×24 ft | $1,252–$1,525 | $3,744–$6,048 |
| House slab | 1,500 sq ft | $3,259–$3,972 | $9,750–$15,750 |
A house slab often includes thickened edges and a base course, so treat the house row as the slab portion only.
How to Calculate Concrete Slab Cost
- Multiply length × width for the area in square feet.
- Multiply the area by $6.50 to $10.50 for the installed range.
- For concrete only, find cubic yards with the calculator and multiply by your price per yard.
- Add base gravel, rebar or mesh, and delivery fees if they apply.
Worked Examples: Slab Cost Step by Step
12×16 ft patio. 192 sq ft × $6.50–10.50 = $1,248–$2,016 installed; concrete $417–$508.
30×40 ft barn slab. 1,200 sq ft × $6.50–10.50 = $7,800–$12,600 installed; 16.30 yd³ of concrete, $2,607–$3,178.
20×20 ft slab at 6 in instead of 4 in. Concrete rises from $869–$1,059 to $1,304–$1,589.
What Is Included in an Installed Slab Price?
An installed price usually covers excavation, forms, base, concrete, placing, finishing and curing; reinforcement, permits and removal of an old slab often cost extra. Ask each contractor what the quote includes.
Concrete Slab Cost per Square Foot by Thickness
| Thickness | Concrete per sq ft (with 10%) |
|---|---|
| 4 in | $2.17–$2.65 |
| 5 in | $2.72–$3.31 |
| 6 in | $3.26–$3.97 |
Installed prices stay around $6.50–10.50 per sq ft (Concrete Network); thicker slabs move toward the top of that range because they use more concrete.
Concrete Slab Cost Calculator FAQ
How much does a 20×20 concrete slab cost?
A 20×20 ft concrete slab costs about $2,600–$4,200 installed at 4 in thick, or $869–$1,059 for the concrete alone.
How much does a 40×60 concrete slab cost?
A 40×60 ft slab (2,400 sq ft) costs about $15,600–$25,200 installed at 4 in, or $5,215–$6,356 for the concrete.
How much does it cost to pour a 24×24 garage slab?
A 24×24 ft garage slab costs about $3,744–$6,048 installed at 4 in, or $1,252–$1,525 for the concrete.
How much should a 12×16 concrete slab cost?
A 12×16 ft slab costs about $1,248–$2,016 installed at 4 in.
How much should a 30×40 slab cost?
A 30×40 ft slab costs about $7,800–$12,600 installed at 4 in.
How much would it cost to pour a 12×20 concrete slab?
A 12×20 ft slab costs about $1,560–$2,520 installed at 4 in.
How much would a 20×60 concrete slab cost?
A 20×60 ft slab costs about $7,800–$12,600 installed at 4 in.
Does a 4-inch concrete slab need rebar?
Not by code: the 2021 IRC treats slab-on-ground reinforcement as optional (R506.2.4); see the rebar calculator for slabs.
Next step
Check thickness in our slab thickness guide and the base on gravel base calculator before you compare quotes.
Official sources
Last reviewed 2026-11-05. Numbers come from our tested engine; see how we calculate and our sources.