How the calculation works
Net yd³ = length × width × thickness in inches ÷ 324. Add allowance, round to the supplier increment, apply any minimum billed volume, then add the entered charges.
A worked example
A 20 × 20 ft slab at 4 in with 10% extra needs 5.4321 yd³. A quarter-yard order increment gives 5.50 yd³. At an illustrative $160/yd³, material is $880 before fees.
Typical concrete slab cost per square foot (2026)
Published 2026 cost guides put a plain, installed concrete slab at roughly $6 to $12 per square foot. HomeGuide (February 2026) reports $6–$12 installed, with materials about $3–$7 and labor about $3–$5 per square foot. Concrete Network (updated July 2026) lists $6.50–$10.50 for a plain slab. Colored, stamped or decorative finishes cost more.
| Slab thickness | Typical installed cost |
|---|---|
| 4 in | $6–$8 per ft² |
| 6 in | $8–$10 per ft² |
| Slab size | Area | At $6–$12 per ft² |
|---|---|---|
| 10 × 10 ft | 100 ft² | $600–$1,200 |
| 12 × 12 ft | 144 ft² | $864–$1,728 |
| 20 × 20 ft | 400 ft² | $2,400–$4,800 |
| 24 × 24 ft | 576 ft² | $3,456–$6,912 |
| 30 × 30 ft | 900 ft² | $5,400–$10,800 |
Driveway and patio cost ranges
Project ranges are wider because thickness, reinforcement, base work, access and finish vary. HomeGuide reports concrete driveways at $6–$15 per square foot installed and patios at $4–$12. Concrete Network lists $5–$21 for driveways and $5–$18 for patios. Material-only ready-mix pricing is explained in concrete cost per yard.
Use these ranges to sanity-check a quote, not to replace one. The calculator above starts with blank prices so your own supplier and contractor figures drive the budget. Add base material and the reinforcement your plan specifies, such as rebar or wire mesh sheets, as separate lines.
How much does a concrete slab cost per square foot?
Published 2026 guides put a plain installed slab at roughly $6 to $12 per square foot. HomeGuide reports about $6–$8 for a 4-inch slab and $8–$10 for a 6-inch slab. A 20 × 20 ft slab at $6–$12 per square foot is $2,400–$4,800. Your local quotes decide the real figure.
How much will my concrete slab cost?
Calculate the billed volume using your dimensions, selected allowance and supplier increment. Multiply by your quoted rate and add confirmed delivery, labor, base, reinforcement, other charges and tax. There is no universal local price built into this tool.
Why does the budget say some costs are unknown?
A blank charge has not been confirmed. The tool shows known costs so far and marks the budget incomplete. Enter zero only after checking that a charge does not apply.
What to check before using the result
- Prices start blank because we do not have your supplier quote.
- Blank charges remain unknown. A material subtotal is not a completed installed budget.
Save this estimate to compare it later, or print a copy. Saved estimates live in this browser. Shared links contain the inputs you choose to share.
References & product information
- HomeGuide: How Much Does a Concrete Slab Cost? (February 2026)
- Concrete Network: Concrete Prices (updated July 2026)
- QUIKRETE Concrete Mix #1101 data sheet
Method prepared 2026-10-21. See our calculation and editorial methods. Spotted a problem? Tell us about it.