Full slab scope and price
Free Concrete Slab Cost Calculator
This free concrete slab cost calculator prices the details that actually move a quote: finish type, thickened edges and a vapor barrier, on top of concrete, base, reinforcement and labor.
Reviewed September 1, 2026 by Sam Johnson from the Concrete Calculators Editorial Team. Published formulas and editable planning assumptions are identified below.
Estimated total cost
point estimate, see range below
- Likely range
- $2,965 to $3,976
- Concrete to order
- 5.50 cu yd
- Concrete cost
- $908
- Gravel base
- 6.9 tons, $222
- Rebar grid
- $440
- Labor and finish
- $1,800
- Control joints
- 2 cuts, 10.0 ft grid
- Cost per area
- $8.42 per sq ft
Plants add a short load fee, often $75 to $150, on orders under about 8 yards. Add it when you compare quotes.
Take this estimate with you
How the concrete slab cost calculator works
Concrete, base, reinforcement and labor are priced the same way as a plain pad: volume with waste at your ready mix price, crushed stone at $45 a yard, mesh or rebar by the square foot, and $4.50 a square foot to form, pour and broom finish.
What makes a slab cost more than a pad
On top of that, the concrete slab cost calculator prices what makes a slab a slab. The finish: broom is included in the labor rate, smooth trowel adds $0.50, exposed aggregate $2.00 and stamped $8.00 per square foot, our stated assumptions for a basic single pattern job.
Thickened edges add a 12 by 12 inch perimeter footing rolled into the pour, priced as extra concrete. The vapor barrier is 10 mil poly at $0.50 a square foot installed. When and why a barrier is required is covered in the vapor barrier under concrete slab guide.
A worked concrete slab cost example
Worked example: a 20 by 20 broom finished slab at 4 inches with a rebar grid orders 5.5 yards for $908, sits on 6.9 tons of base for $222, carries $440 of rebar and $1,800 of labor. Point estimate $3,370, likely range $2,965 to $3,976. Tick thickened edges and the vapor barrier and the order grows to 7.75 yards and about $3,941.
Control joint spacing
The results panel also counts control joints for you, spaced at 30 times the slab thickness with a 15 ft cap, the PCA rule of thumb. A 4 inch slab wants cuts on a 10 ft grid, and skipping them is how a slab picks its own crack pattern.
Just counting yards and bags? That is the concrete calculator. A simple shed or equipment base prices faster on the concrete pad cost calculator, which skips the finish options on purpose.
Concrete slab cost by size
A 4 inch broom finished slab on a gravel base with a rebar grid runs about $8.40 per square foot installed, and most jobs land between $7.40 and $9.90. Small slabs sit at the high end because the truck minimum spreads over less area.
Every row below comes from this concrete slab cost calculator at its default prices. Change the thickness, finish or your local ready mix price and your number moves with it.
| Slab size | Area | Concrete to order | Point estimate | Likely range | Per sq ft |
|---|---|---|---|---|---|
| 10x10 ft | 100 sq ft | 1.5 cu yd | $863 | $759 to $1,018 | $8.63 |
| 12x12 ft | 144 sq ft | 2 cu yd | $1,216 | $1,070 to $1,435 | $8.45 |
| 16x20 ft | 320 sq ft | 4.5 cu yd | $2,712 | $2,387 to $3,200 | $8.48 |
| 20x20 ft | 400 sq ft | 5.5 cu yd | $3,370 | $2,965 to $3,976 | $8.42 |
| 24x24 ft | 576 sq ft | 8 cu yd | $4,866 | $4,282 to $5,741 | $8.45 |
| 30x30 ft | 900 sq ft | 12.25 cu yd | $7,561 | $6,654 to $8,922 | $8.40 |
| 40x60 ft | 2,400 sq ft | 32.75 cu yd | $20,177 | $17,756 to $23,809 | $8.41 |
Why the per square foot rate barely moves
Past about 150 square feet the rate flattens near $8.40 because the two biggest lines, concrete and labor, both scale with area. What changes the rate is the spec, not the size: a stamped finish adds $8 per square foot at any size, and thickening from 4 to 6 inches adds roughly $1.15.
Concrete slab cost by finish
The finish is the biggest single lever on slab price. All rows are a 20 by 20 ft slab at 4 inches with gravel base, rebar grid, labor and our default prices.
| Finish | Point estimate | Likely range | Per square foot |
|---|---|---|---|
| Broom | $3,370 | $2,965 to $3,976 | $8.42 |
| Smooth trowel | $3,570 | $3,141 to $4,212 | $8.92 |
| Exposed aggregate | $4,170 | $3,669 to $4,920 | $10.42 |
| Stamped | $6,570 | $5,781 to $7,752 | $16.42 |
Stamped swings the most in real quotes. Pattern count, color hardener and the crew's speed all move it, so treat the range as a starting point and get three bids.
What the slab cost calculator does not include
- Engineering. This tool prices flatwork, and a slab that carries building loads or sits on bad soil needs a design, not a calculator.
- Demolition of an old slab, tree roots, or hauling spoil off site.
- A pump when the truck cannot reach the forms. Straight control joints on the grid the results panel counts are part of the labor rate, but decorative sawcut patterns are not.
- Winter protection. Blankets and accelerator on a cold pour add real money.
- Slope, drains and haunches for a garage or wash bay. Ask for them in the quote by name. If the slab carries a block wall, size that wall with the concrete block calculator.
Straight answers
Concrete slab cost questions
Open a question for the practical answer, including the assumptions behind the number.
What should a concrete slab quote include?
Thickness, mix strength in psi, base depth and material, reinforcement type and spacing, finish, control joint layout, waste handling and cleanup. If a quote is one number with none of that, you cannot compare it to the next one.
How is this different from the pad cost calculator?
The concrete slab cost calculator adds the slab specific options: finish type, thickened edges and a vapor barrier. The pad tool stays simple on purpose for shed bases and equipment pads where broom finish and no barrier is the normal spec.
How much does a 20 by 20 concrete slab cost?
About $3,370 broom finished using the concrete slab cost calculator defaults, with a likely range of $2,965 to $3,976. The same slab stamped roughly doubles to $6,570 because the finish adds $8 per square foot.
Does a slab need a vapor barrier?
Under anything enclosed or conditioned, yes. Moisture migrating up through the slab wrecks flooring and coatings. An open patio or walkway can skip it.
What do thickened edges add to the price?
On a 20 by 20 slab the 12 by 12 inch perimeter footing adds about 2.25 yards of concrete, roughly $370 at our default price. Codes commonly ask for thickened edges when the slab supports walls, so check before you pour, not after.
How much does a 20x20 concrete slab cost?
About $3,370 for a 4 inch broom finished slab on a gravel base with a rebar grid, with a likely range of $2,965 to $3,976. That is 5.5 cubic yards of concrete and roughly $8.42 per square foot installed.
How much does it cost to pour a 40x60 slab?
About $20,177 at 4 inches, in a likely range of $17,756 to $23,809. A slab that size takes 32.75 cubic yards, so it is four truck loads and the per yard price becomes the number worth negotiating.
What does a 30x30 concrete slab cost?
About $7,561 installed at 4 inches, ranging from $6,654 to $8,922, using 12.25 cubic yards. Going to 6 inches adds roughly $1,030 in concrete on a slab this size.
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Concrete guides to read next
- How thick should a concrete driveway be
4 inches is the minimum, 5 is the smart pour. Thickness by vehicle, climate and cost.
- Vapor barrier under concrete slab
When it is required, what mil to use, and why the sand layer argument was settled.
What changed on this page
- Per field unit choice added.
- Copy, email and print estimate actions added.
- Control joint count added, using the PCA rule of about 30 times slab thickness.
Prices and formulas are reviewed on the schedule described in our methodology.