A standard 4-inch concrete slab costs roughly $4 to $8 per square foot installed in 2026, with $6 per square foot a fair national midpoint for a plain, broom-finished slab on flat, prepared ground. That means a typical 20 × 20 ft (400 sq ft) slab runs about $2,400, and a 24 × 24 ft garage pad about $3,450. The exact number depends on thickness, finish, site prep, and where you live — the fastest way to price your slab is to run the dimensions through the free concrete calculator, which separates materials from labor. This piece shows the data behind those figures.
The per-square-foot ranges
Concrete pricing has two layers: the material (ready-mix concrete, sold by the cubic yard) and the installed price (material + labor + finishing). For a standard residential slab in 2026:
| Line item | Typical 2026 range | Notes |
|---|---|---|
| Ready-mix concrete | $120–$180 / cubic yard | Delivered; short-load fees extra |
| Material only, 4" slab | $1.75–$2.50 / sq ft | ~1 yd covers 81 sq ft at 4" |
| Installed, plain 4" slab | $4–$8 / sq ft | Most homeowners land near $6 |
| Installed, 6" slab | $6–$10 / sq ft | Driveways, heavy loads |
| Stamped or colored finish | +$8–$18 / sq ft | Decorative premium |
A 4-inch slab uses about one cubic yard of concrete per 81 square feet (a cubic yard is 27 cubic feet; at 4 inches = ⅓ foot deep, one yard spreads across 81 sq ft). That single ratio is what the yardage calculator is built on, and it's the number contractors quote from.
Slab cost by size (installed, plain 4-inch)
Using the $6/sq ft national midpoint for a standard finished slab:
| Slab size | Area | Concrete needed | Est. installed cost |
|---|---|---|---|
| 10 × 10 | 100 sq ft | ~1.3 yd³ | ~$600 |
| 12 × 12 | 144 sq ft | ~1.8 yd³ | ~$865 |
| 16 × 20 | 320 sq ft | ~4.0 yd³ | ~$1,920 |
| 20 × 20 | 400 sq ft | ~4.9 yd³ | ~$2,400 |
| 24 × 24 | 576 sq ft | ~7.1 yd³ | ~$3,450 |
| 30 × 40 | 1,200 sq ft | ~14.8 yd³ | ~$7,200 |
| 40 × 60 | 2,400 sq ft | ~29.6 yd³ | ~$14,400 |
Concrete volumes include a 10% waste allowance, which is standard practice — spillage, uneven subgrade, and over-excavation mean you almost never place the theoretical minimum. Bigger pours get slightly cheaper per square foot because labor and delivery are spread over more area, so treat the large-slab numbers as a ceiling.
What moves the price
Five factors explain most of the spread between the low and high end:
Thickness. Going from 4 inches to 6 inches adds 50% more concrete volume. A 6-inch slab is standard for driveways and anything carrying vehicle weight.
Site preparation. A flat, compacted, ready-to-pour pad is the cheap case. Grading, removing sod, hauling in gravel base, or building forms on a slope all add labor before a single yard is placed.
Finish. A plain broom finish is baseline. Smooth-troweled, colored, stamped, or exposed-aggregate finishes each add materials and skilled labor — a stamped patio can cost more than double a plain slab.
Reinforcement. Wire mesh or rebar, vapor barrier under the slab, and thickened edges (for footings) all add cost but are often required by code.
Region and season. Ready-mix prices and labor rates vary widely by metro, and cold-weather pours may need additives or blankets.
How to price your exact slab
Rules of thumb get you in the ballpark, but the real number depends on your dimensions, thickness, and local ready-mix price. The concrete slab cost calculator takes your length, width, and thickness and returns the cubic yards, the number of 40 / 60 / 80-lb bags if you're mixing by hand, and an installed-cost estimate you can adjust to your local price per yard. For footings, columns, and walls, the main concrete calculator handles those shapes too.
Rule of thumb: budget $6 per square foot for a plain 4-inch slab on prepared ground, then adjust up for thickness, finish, and site work. Above about one cubic yard, ready-mix delivery is almost always cheaper than bagged concrete.
Figures reflect typical 2026 U.S. residential pricing and are estimates for planning; get local quotes before you budget a project. Volumes shown use the Vyze concrete methodology with a 10% waste allowance.