A basic 4-inch concrete slab costs $6 to $10 per square foot installed, averaging about $8 per square foot across the United States. A 10×10 slab runs $600 to $1,000, a 12×12 runs $860 to $1,440, and a 20×20 runs $2,400 to $4,000. Enter your dimensions below for a state-adjusted estimate.
Thickness, finish, and reinforcement are the three biggest add-ons beyond square footage, and each is built into the calculator so you can compare options side by side.
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Your Planning Estimate Breakdown
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Range breakdown
| Component | Low | Average | High |
|---|---|---|---|
| Base installation | - | - | - |
| Thickness adjustment | - | - | - |
| Finish adjustment | - | - | - |
| Calculated subtotal | - | - | - |
Concrete slab cost by size
These ranges assume a standard 4-inch slab with a broom finish and no reinforcement.
| Slab size | Square feet | Typical range | Average cost |
|---|---|---|---|
| 10×10 | 100 | $600–$1,000 | $800 |
| 12×12 | 144 | $860–$1,440 | $1,150 |
| 20×20 | 400 | $2,400–$4,000 | $3,200 |
| 24×24 garage | 576 | $3,460–$5,760 | $4,600 |
Concrete slab cost by thickness, finish, and reinforcement
Every upgrade below is added on top of the base price per square foot.
| Upgrade | Added cost per sq ft |
|---|---|
| 5-inch slab (vs. 4-inch) | +$0.75–$1.50 |
| 6-inch slab (vs. 4-inch) | +$1.50–$3.00 |
| Smooth trowel finish | +$0.50 |
| Stained finish | +$3.25 |
| Stamped finish | +$4.25 |
| Wire mesh reinforcement | +$0.50–$1.25 |
| Rebar reinforcement | +$1.00–$2.50 |
What affects the price
- Thickness: most patios and walkways use 4 inches, while driveways and garages typically need 5 to 6 inches to carry vehicle weight.
- Finish: broom is standard; smooth trowel, staining, and stamping each add cost per square foot.
- Reinforcement: wire mesh adds $0.50–$1.25 per square foot, while rebar adds $1.00–$2.50 per square foot.
- Concrete volume: divide square feet by 81 to get cubic yards for a 4-inch slab — a 12×12 slab needs about 1.8 cubic yards.
- Site conditions: access, grading, and distance from the concrete truck all affect the quote.
What the estimate includes and does not include
The estimate includes concrete delivery, forming, pouring, finishing, and basic grading. It does not include permits, excavation of poor soil, reinforcement unless specified, finishes beyond a broom finish, or removal of an existing slab.
Worked Slab Volume Example
For a 12×12 slab at 4 inches, the quantity before waste is 12 × 12 × (4 ÷ 12) ÷ 27 = 1.78 cubic yards. A 10% allowance raises the planning order to 1.96 cubic yards. Suppliers may sell in half-yard increments and apply short-load minimums, so compare the rounded delivery quantity in the price-per-yard estimator with bagged-mix yield and labor.
Use the Same Scope When Comparing Quotes
Ask every bidder to price the same dimensions, finished elevation, excavation, base depth and compaction, reinforcement, concrete strength, placement method, finish, joints, curing, cleanup, permits, and tax. A low square-foot rate can omit preparation or fixed charges that appear later.
Frequently asked questions
Should I pour a 4-inch or 6-inch slab?
Four inches is a common estimating assumption for light-duty patios and walks. Vehicle, building, equipment, or concentrated loads may require more thickness or local thickening. Soil, base, reinforcement, concrete strength, climate, and local code also matter, so do not treat a calculator selection as a structural specification.
How many cubic yards of concrete do I need?
Divide square feet by 81 for a 4-inch slab. A 12×12 slab is about 1.8 cubic yards; add extra volume for thicker pours.
How much does a garage slab cost?
A 24×24 garage slab (576 square feet) typically costs $3,460 to $5,760, averaging about $4,600 installed.
Does my slab need rebar?
Rebar, welded wire reinforcement, fiber, or no reinforcement may be specified depending on the slab, loads, shrinkage-control plan, and local practice. Reinforcement can help hold cracks but does not replace base preparation, joints, curing, or adequate thickness. Confirm the construction specification locally.
Related tools
- Concrete Patio Cost Calculator
- Concrete Driveway Cost Calculator
- Concrete Price Per Yard
- All concrete project costs
Sources and update policy
Figures are planning estimates compiled from public contractor-cost data and refreshed monthly. See how we build estimates on our methodology page.
Estimate transparency
How this estimate was prepared
- Prepared by
- GoHomeCost Cost Data Team
- Last reviewed
- August 24, 2026
- Update cycle
- Public price inputs checked monthly
Calculation method: Project quantity is multiplied by editable low, typical, and high unit rates. Selected location adjustments, waste, fixed charges, and minimum-job rules are then applied and shown in the result.
Public references used on this page:
This is a planning estimate, not a quote or structural specification. Check product yields, local code, site conditions, and written contractor bids before purchasing materials or building.
Read the full methodology Report a price or calculation issue