Concrete Slab Cost Calculator
Updated Formulas shown
Material is only part of a slab's cost. This calculator adds labor and finishing per square foot. A 20 × 20 ft slab at 4 inches uses about 5.3 yd³ of concrete; at $175/yd³ and $4.50/ft² labor, expect around $2,700.
- Concrete
- 5.33 yd³
- Material
- $933
- Labor & finishing
- $1,800
- Area
- 400 ft²
Typical 2026 US ranges: ready-mix $150–$200/yd³ delivered, installed slabs $6–$12 per ft² including base, forms, rebar/mesh and finishing.
How to use it
- Enter your local ready-mix price (call two plants — prices vary by region).
- Labor and finishing typically run $3–$7 per ft² (forms, base prep, placing, broom or trowel finish).
- Add extras separately: demolition, gravel base, rebar/mesh, stamping or color, permits.
Related calculators
- Concrete CalculatorFree concrete calculator: enter length, width and thickness to get cubic yards, 40/60/80 lb bag counts and ready-mix cost.
- Gravel CalculatorHow much gravel do you need? Enter area and depth to get cubic yards and tons, with cost per ton.
- Rebar CalculatorCalculate rebar for a concrete slab: bars each way, total linear feet and 20 ft pieces including laps.
Frequently asked questions
How much does a 20x20 concrete slab cost?
Roughly $2,400–$4,800 installed in 2026 for a plain 4-inch slab ($6–$12 per ft²). Stamped or colored concrete costs more.
What is the cost per square foot of concrete?
Plain installed slabs average $6–$12 per ft² in 2026; material alone is about $2–$3 per ft² at 4 inches.
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Estimates only. Check quantities with your supplier or contractor before ordering.