Concrete Slab Cost per Square Foot
Slab Cost per Square Foot, by Scenario
Typical 2026 US figures for a 4-inch slab; thicker pours scale the concrete lines almost exactly linearly.
| Scenario | Per ft² | Includes |
|---|---|---|
| Materials only (4 in., ready-mix) | $2.00–$2.25 | Concrete delivered, nothing else |
| Materials only (4 in., bagged) | $3.50–$4.00 | 45 bags per yard, at your back's expense |
| Gravel base + reinforcement | $1.00–$2.00 | 4 in. compacted base, mesh or rebar |
| DIY total (materials + base) | $3.50–$4.50 | Your labor is the discount |
| Pro-installed patio / walkway | $6–$10 | Forms, base, pour, finish, cure |
| Pro-installed driveway | $7–$12 | Thicker pour, heavier base, more finishing |
The Per-Square-Foot Math, Done Once
$ per ft² = (price per yd³ ÷ 27) × thickness (ft) 4-inch slab: ($165 ÷ 27) × 0.333 = $2.04/ft² 6-inch slab: ($165 ÷ 27) × 0.5 = $3.06/ft²
Two facts fall out of that formula. First, thickness raises cost linearly — a 6-inch driveway carries 50% more concrete than a 4-inch patio over the same footprint. Second, region only shifts the first factor: swap $165 for your local per-yard quote and the rate moves with it, which is exactly how the cost-per-yard ranges translate into square feet.
Worked Example: a 12 × 20 Slab
- Footprint 240 ft² × $2.04 = $489 in concrete (2.96 yd³) — order 3.5 yd³ with the allowance, ≈ $578.
- Gravel base, 4 inches over 240 ft²: ≈ 3 yd³ of crushed stone, $150–$250.
- Mesh or rebar: $60–$150. Forms and stakes: $60–$120 in lumber.
- DIY total: roughly $850–$1,100. Contractor installed at $7–$10/ft²: $1,700–$2,400.
What Each Price Level Actually Includes
"$2 per square foot" and "$8 per square foot" are both true, of different scopes. Materials-only covers concrete at the curb. A professional number bundles site prep and grading, form lumber and stakes, a compacted base, reinforcement, the pour itself, finishing (screed, bull float, broom or trowel), control joints, and curing — plus insurance and haul-off. When comparing contractor quotes per square foot, ask which of those lines are included; a low rate that excludes the base is not a low price.
Frequently Asked Questions
How much does a 12×20 concrete slab cost?
In materials, about $580 in ready-mix plus $250–$400 for base, reinforcement and forms — call it $850–$1,000 DIY. Professionally installed at $7–$10 per square foot, expect $1,700–$2,400.
How much does a 4-inch slab cost per square foot installed?
Typically $6–$10 for patios and walkways, $7–$12 for driveways where base and thickness requirements are higher. Region, site access and finish level move the rate more than the concrete itself.
Does a thicker slab cost proportionally more?
The concrete does — cost per square foot scales linearly with thickness ($2.04 at 4 inches, $3.06 at 6 inches at $165/yd³). Installed prices move less than proportionally because labor mostly scales with area, not thickness.
What's the cheapest way to get a slab?
Do the site work and forms yourself, order ready-mix rather than bagged, and hire out only the finish if you must — finishing skill is what shows forever. The concrete itself is rarely the line item worth cutting; $2/ft² of material is a third of an installed slab's cost.