How Much Does a Concrete Slab Cost?
Cost by size, thickness, finish, and prep work. Patio, garage, driveway, and foundation slabs.
Quick answer
$4-$8 per square foot for a basic 4-inch slab.
A 20x20 patio slab: $2,000-$4,000.
Concrete Slab Cost Estimator
Estimate your slab cost based on size, thickness, reinforcement, and finish type.
Common sizes: 100 (10x10), 400 (20x20), 900 (30x30)
Standard residential thickness
Estimated Total
$3,700
Range: $3,145 to $4,625
Materials
$1,215
Labor
$1,485
Site prep (excavation, gravel, forms)
$1,000
Often excluded from low-ball quotes
All-in price per sq ft
$9.3/sqft
Including site prep, pour, and finishing
Cost by Slab Size
Standard 4-inch thickness with broom finish. Prices include site prep, concrete, and labor.
| Slab Size | Sq Ft | Low | High | Typical Use |
|---|---|---|---|---|
| 10 x 10 | 100 | $600 | $1,200 | Small patio, shed base |
| 20 x 20 | 400 | $2,000 | $4,000 | Patio, 1-car garage |
| 30 x 30 | 900 | $4,500 | $9,000 | 2-car garage, large patio |
| 40 x 60 | 2,400 | $12,000 | $24,000 | 3-car garage, workshop |
Thickness and Reinforcement
Thickness is the biggest driver of concrete volume cost. Choose based on what the slab will support.
4 inch (standard)
$4-$8/sqft
Patios, walkways, shed bases. Fine for foot traffic and light loads.
6 inch (vehicle-rated)
$6-$12/sqft
Driveways, garages, any slab supporting cars or trucks.
Rebar reinforcement
+$1-$2/sqft
Adds tensile strength. Required for most garage and driveway slabs.
| Reinforcement Type | Cost per Sq Ft | Best For |
|---|---|---|
| No reinforcement | $0 | Small decorative slabs in stable soil |
| Wire mesh | $0.50-$1.00 | Patios, walkways, light residential use |
| Rebar (#3 or #4) | $1.00-$2.00 | Garages, driveways, heavy vehicle traffic |
| Fiber-reinforced concrete | $0.75-$1.50 | Crack resistance, often used alongside rebar |
Finish Options and What They Cost
Finish affects both appearance and slip resistance. Broom finish is the default. Everything else is an upgrade.
| Finish Type | Cost per Sq Ft | Notes |
|---|---|---|
| Broom finish | Included | Standard texture. Non-slip, durable, no added cost. |
| Stamped concrete | $8-$18/sqft | Mimics stone, brick, or wood. Most popular decorative option. |
| Exposed aggregate | $8-$15/sqft | Surface washed to reveal stones. Naturally non-slip. |
| Colored concrete | $6-$12/sqft | Integral pigment mixed in. Permanent, fades gradually over years. |
| Polished concrete | $6-$12/sqft | Ground and buffed to a sheen. Common indoors. Requires sealing. |
Site Preparation Costs
Prep work is often excluded from low-ball quotes. Make sure your quote is itemized.
| Prep Item | Typical Cost | Notes |
|---|---|---|
| Grading and excavation | $500-$2,000 | Depends heavily on slope and soil condition. |
| Gravel base | $1-$2/sqft | 4-6 inch compacted gravel for drainage. Required for most slabs. |
| Forms and framing | $1-$2/sqft | Wood or steel forms that shape the slab edges. |
| Rebar or mesh | $0.50-$2/sqft | See reinforcement section above. |
Get itemized quotes
Always ask contractors to break out prep, concrete, finishing, and curing separately. A quote of "$3/sqft" likely excludes most of the prep work. Final costs including full site prep typically run $6-$12 per square foot for standard slabs.
Frequently Asked Questions
How much does a concrete slab cost per square foot?
A standard 4-inch slab costs $4-$8 per square foot installed, including concrete, labor, and a broom finish. Thicker slabs for vehicles run $6-$12. Decorative finishes like stamped concrete add $4-$10 on top of the base price.
How much does a 20x20 concrete slab cost?
A 20x20 slab (400 sq ft) runs $2,000-$4,000 for a standard 4-inch pour. Upgrading to 6 inches for a garage brings it to $3,200-$6,400. Stamped concrete on the same footprint costs $4,000-$9,600.
Do I need rebar in a concrete slab?
Rebar or wire mesh is recommended whenever the slab will bear vehicle weight or spans more than 12 feet. Rebar adds $1-$2 per square foot. Wire mesh is cheaper ($0.50-$1) but provides less tensile strength. Patios in stable soil can often use mesh alone.
What is included in a concrete slab quote?
A complete quote covers excavation, grading, gravel base, forms, concrete, finishing, and curing. Site prep alone can be $500-$2,000. If a quote seems low, ask specifically what prep work is excluded. Always get itemized breakdowns before signing anything.