Quick answer
Concrete slab cost typically runs $6 to $14 per square foot in 2026 for a standard 4-inch residential slab, including base prep, reinforcement, forming, placing and finishing. Thicker slabs, heavy reinforcement, poor access and commercial tolerances push the number higher. Material alone is often $3 to $5 per square foot.
- Material is quoted per cubic yard, but bids are compared per square foot, so thickness drives the conversion.
- A 4-inch slab uses about 0.0123 cubic yards of concrete per square foot; a 6-inch slab uses about 0.0185.
- Finishing, base prep and reinforcement usually cost more than the concrete itself.
- Get a takeoff from the drawings before you price; square-foot rules of thumb miss thickness and detail.
What Is the Average Concrete Slab Cost per Square Foot?
For a complete slab-on-grade installation, typical U.S. residential and light commercial pricing usually falls in the $6–$14 per square foot range. Plain 4-inch slabs with minimal reinforcement sit at the low end. Thicker, reinforced, finished slabs—especially those that are structural or exposed—push toward the high end. This is an installed cost, not just the ready-mix invoice. It includes material, labor, equipment, forms, base preparation, finishing, and curing.
The concrete slab cost per square foot varies by region, season, site access, thickness, reinforcement, finish, and whether the slab is interior, exterior, or structural. A slab in a tight urban lot with limited truck access costs more than the same square footage on an open rural site. Winter pours with heated water and blankets add cost. A power-troweled warehouse floor costs more than a simple broom finish.
A slab is priced in three ways: per square foot (installed), per cubic yard (concrete only), and per square meter (metric projects). The square footage method is what owners and general contractors use for budgeting. The cubic yard method is what the ready-mix supplier uses for the concrete itself. The square meter method appears on international or metric-spec projects. Any single national number is a planning benchmark, not a bid. To get a real number for your project, you need a takeoff that reflects your drawings, specs, and local market. For a detailed concrete takeoff, see Concrete Estimating Services.
Treat any published per-square-foot figure as a starting point. Your actual concrete slab cost depends on your plans, site, and local labor rates.
Concrete Slab Price per Yard vs. Cost per Square Foot
Ready-mix concrete is sold by the cubic yard. Slabs are estimated by the square foot. You convert between them with thickness. The volume formula is: cubic yards = (length ft × width ft × thickness ft) ÷ 27. For example, a 20 ft × 30 ft slab at 4 inches thick is (20 × 30 × 0.3333) ÷ 27 = 7.41 cubic yards. That is the concrete volume, before waste.
The concrete slab price per yard typically covers material only—the truck delivering ready-mix. It does not include rebar, wire mesh, vapor barrier, gravel base, formwork, pump, labor, or finishing. Those items are separate line items in your estimate. Short loads, small quantities, Saturday pours, fiber mesh, and admixtures all change the yard price. A 3-yard load often carries a short-load fee. A pump truck adds a separate mobilization and hourly charge.
A concrete slab cost calculator usually asks for length, width, thickness, and finish to output both cubic yards and installed cost. That is useful for a quick check, but it cannot see your site conditions, reinforcement schedule, or local labor rates. For a material takeoff that separates concrete, reinforcement, and base, see Material Takeoff Services.
Always add a waste factor to your cubic yard calculation. Five to ten percent is common for slab-on-grade.
Worked Example: Cost of a 30 ft × 40 ft Slab
This is an example only, not a quote. Unit costs are assumed for illustration. Swap in your own numbers.
Step 1: Area. 30 ft × 40 ft = 1,200 sq ft.
Step 2: Volume at 4 in thick. Thickness in feet = 4 ÷ 12 = 0.3333 ft. Volume = (1,200 × 0.3333) ÷ 27 = 14.81 cu yd. Add a 7% waste factor: 14.81 × 1.07 = 15.85 cu yd. Round to 16 cu yd.
Step 3: Ready-mix material. At an assumed $165 per cu yd: 16 × $165 = $2,640.
Step 4: Add reinforcement, vapor barrier, base, formwork and labor, finishing and curing.
- Reinforcement: 6×6 W2.9×W2.9 mesh at ~$0.20/sq ft = 1,200 × $0.20 = $240.
- Vapor barrier: ~$0.15/sq ft = 1,200 × $0.15 = $180.
- 4 in gravel base: ~$1.25/sq ft = 1,200 × $1.25 = $1,500.
- Formwork and labor: assume $3.50/sq ft = 1,200 × $3.50 = $4,200.
- Finishing and curing: assume $1.00/sq ft = 1,200 × $1.00 = $1,200.
Step 5: Subtotal and overhead and profit. Subtotal = $2,640 + $240 + $180 + $1,500 + $4,200 + $1,200 = $9,960. Add 15% overhead and profit: $9,960 × 0.15 = $1,494. Total ≈ $11,454, or about $9.55 per sq ft. Show every line so you can swap your own unit costs. For a full quantity takeoff of your slab, see Quantity Takeoff Services.
| Line item | Quantity | Unit cost | Cost |
|---|---|---|---|
| Ready-mix concrete | 16 cu yd | $165/cu yd | $2,640 |
| Wire mesh 6×6 W2.9×W2.9 | 1,200 sq ft | $0.20/sq ft | $240 |
| Vapor barrier | 1,200 sq ft | $0.15/sq ft | $180 |
| 4 in gravel base | 1,200 sq ft | $1.25/sq ft | $1,500 |
| Formwork and labor | 1,200 sq ft | $3.50/sq ft | $4,200 |
| Finishing and curing | 1,200 sq ft | $1.00/sq ft | $1,200 |
| Subtotal | — | — | $9,960 |
| Overhead and profit 15% | — | — | $1,494 |
| Total | — | — | $11,454 |
This example uses a 4-inch slab with mesh. A 6-inch reinforced slab with a power-troweled finish would cost more per square foot.
Concrete Slab Cost per m2 and per Square Meter
Metric drawings and international tenders quote concrete slab cost per m2, so you need a clean conversion before you compare anything. One square meter equals 10.7639 square feet. A slab priced at $9.55 per sq ft is therefore about $102.80 per m2 ($9.55 × 10.7639 = $102.80).
Go the other way by dividing. If a tender shows a unit cost of $145 per square meter, divide by 10.7639 to get $13.47 per sq ft ($145 ÷ 10.7639 = $13.47). Do the same for volume: one cubic meter equals 1.308 cubic yards, so 12 m3 of concrete is 15.70 cu yd (12 × 1.308 = 15.70).
U.S. ready-mix suppliers still batch and sell by the cubic yard, even when the drawings are metric, so your material buyout stays in cubic yards while your cost reporting may be per m2. Never mix the two systems in one bid. Convert both the quantity and the unit price, or your concrete slab cost per square meter will be wrong by a factor of roughly ten.
Check which unit the supplier's quote uses before you convert. Mixing cubic yards with cubic meters is the most common metric error in concrete bids.
Concrete Slab Cost Breakdown by Line Item
A slab-on-grade bid is a stack of line items, not one number. The table below shows typical installed cost ranges per square foot for each component, from excavation through overhead and profit. Ranges vary by region, scope and date, so treat them as planning figures and price your own project from the drawings.
| Line item | Unit | Typical installed cost range | Notes |
|---|---|---|---|
| Excavation and grading | per sq ft | $0.50–$1.50 | Strip topsoil, proof-roll subgrade, haul off spoils |
| Gravel base | per sq ft | $0.75–$1.75 | 4 in. of compacted crushed stone, typical |
| Vapor barrier | per sq ft | $0.15–$0.40 | 10–15 mil under-slab membrane, taped laps |
| Formwork | per sq ft | $0.75–$2.00 | Edge forms, keyways, blockouts |
| Reinforcement | per sq ft | $0.60–$1.50 | #4 rebar at 18 in. o.c. or 6×6-W2.9 mesh |
| Ready-mix concrete | per sq ft | $3.50–$6.00 | 4 in. slab, 4,000 psi, includes waste |
| Placement and screeding | per sq ft | $0.75–$1.50 | Chute, buggy or pump; laser screed on large pours |
| Finishing | per sq ft | $0.75–$2.50 | Broom, trowel or exposed aggregate |
| Curing and sealing | per sq ft | $0.20–$0.60 | Cure-and-seal compound or wet cure |
| Overhead and profit | per sq ft | $0.75–$2.00 | Mobilization, supervision, margin |
| Total installed slab | per sq ft | $8.70–$19.75 | Sum of the components above, not a separate line |
The total row is the sum of the components, not an extra charge. If your finishing spec is a hard-trowel floor for a warehouse, the finishing line moves toward the top of its range, and if the slab is small or access is tight, the placement line does too. For a full takeoff of every component, see our concrete estimating services.
Build your own total by adding the components you actually need. A slab with no vapor barrier and no seal still needs excavation, base, forms, concrete and labor.
Send Your Slab Plans for a 48-Hour Takeoff
Upload your drawings and we will return a line-item concrete slab takeoff with quantities, waste factors and a bid-ready cost breakdown within 48 hours.
Concrete Slab Cost by Thickness: 4, 5, 6 and 8 Inches
Thickness drives concrete volume, and volume drives material cost. Everything else on the slab moves less. A 4 in. slab needs 1.23 cu yd per 100 sq ft, a 5 in. slab needs 1.54 cu yd, a 6 in. slab needs 1.85 cu yd, and an 8 in. slab needs 2.47 cu yd, all before waste.
Example: 1,000 sq ft at 4 in. is 12.3 cu yd, and at 8 in. it is 24.7 cu yd. Doubling thickness roughly doubles the concrete, but it does not double the total installed cost, because excavation, base, vapor barrier and much of the labor are tied to area, not depth.
Thicker slabs pull other costs with them. An 8 in. slab usually carries heavier reinforcement, needs deeper edge forms, and on interior pours may require a concrete pump because the mix is harder to place by chute. Thickness is set by design, not by price: ACI 318 governs structural slabs, while the IRC and IBC give prescriptive minimums for common residential and light commercial work. For thickness-specific takeoff, see our foundation estimating services.
Do not downsize a slab to save concrete. Thickness is a structural decision; changing it to cut cost can fail inspection or crack in service.
Concrete Slab Cost Factors That Move the Number
The concrete slab cost factors that move the number most are thickness, reinforcement, subgrade, access, finish, climate and schedule. Start with thickness: doubling slab depth nearly doubles the concrete volume, and volume drives the ready-mix line. Reinforcement type and spacing come next. A slab on welded wire mesh at 6x6-W2.9xW2.9 costs less than one on #4 bars at 12 in on center each way, and the concrete estimating services takeoff has to capture both the mesh and the chairs. Subgrade condition adds cost when you need to over-excavate, import structural fill, or add a capillary break and vapor retarder under the slab.
Access decides how the concrete reaches the forms. A truck that can chute directly to the pour is the cheapest method; a concrete pump adds cost but can beat wheelbarrowing on limited-access sites because it cuts labor hours and pour duration. Mix design changes the yard price too. A 2,500 psi mix for a sidewalk costs less than a 4,000 psi mix for a structural slab, and higher psi, lower slump, air entrainment for freeze-thaw exposure, and synthetic fiber all raise the price per cubic yard. In practice, a 4,000 psi air-entrained mix with fiber and a 4 in slump will price above a plain 2,500 psi mix.
Finish type and cure method add cost. A broom finish is standard; a hard-troweled or polished finish adds passes, densifier, and possibly a grinder. Climate matters: winter pours need heated water, accelerators, insulating blankets, and heated enclosures, while hot-weather pours need retarders, evaporation control, and fogging. Schedule pressure adds overtime, night pours, and standby time. Price each factor as a separate line so the total is defensible.
A pump is often cheaper than the labor to wheelbarrow 20 yd³ of concrete, but only if the pump truck can set up within reach of the pour.
Residential vs. Commercial Slab Cost Differences
Residential slabs are usually 4 to 6 in thick, prescriptively reinforced with mesh or rebar, and finished by a small crew. The scope is simple: form, place, screed, float, broom, cure. Commercial and industrial slabs are often 6 to 12 in, designed by an engineer, and may include dowels at construction joints, thickened edges under racking, joint fillers, and dry-shake hardeners. Those details add material and labor, and they need a commercial estimating services takeoff that reads the structural sheets, not just the plan area.
Overhead, bonding, insurance, submittals, and testing raise the unit cost on commercial work. A commercial estimate usually carries a testing allowance for slump, air content, and compressive strength cylinders, plus special inspection where the code requires it. Residential work rarely carries those line items. Division 03 in CSI MasterFormat covers concrete, and commercial estimates are commonly organized by that structure, with 03 30 00 cast-in-place concrete as the parent section. If you price commercial slabs, keep your residential estimating services rates separate from your commercial rates, because the overhead and profit recovery is different.
A rough rule: residential slabs typically run lower per square foot than commercial slabs of the same thickness because of overhead, testing, and detailing. The concrete itself may cost the same per yard; the difference sits in labor burden, supervision, and quality control.
Do not carry a residential unit rate into a commercial bid. The testing, submittals, and joint detailing alone can add several dollars per square foot.
How to Estimate Concrete Slab Cost Step by Step
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Measure the area and confirm the design. Take the slab area from the drawings, then confirm thickness, reinforcement, and joint layout from the structural sheets. A takeoff that misses a thickened edge or a doubled mat under a column will underprice the job. Use blueprint takeoff services if you need the quantities verified before pricing.
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Compute volume and add waste. Use the concrete slab cost formula: Volume (yd³) = Length (ft) × Width (ft) × Thickness (in) ÷ 324. Add a waste factor of 5 to 10 percent for spillage, over-excavation, and uneven subgrade. A 30 ft × 40 ft slab at 6 in is 30 × 40 × 6 ÷ 324 = 22.2 yd³; at 8 percent waste, order 24.0 yd³. The cost of concrete slab depends heavily on this volume calculation, so double-check your math before moving on.
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Price each line item separately. Ready-mix, reinforcement, vapor barrier, base course, forms, labor, finishing, and curing should each carry their own quantity and unit cost. Keep the reinforcement takeoff in pounds or in square feet of mesh, and keep the vapor barrier in square feet with lap. This is where a concrete slab cost estimator or estimating software helps, but the takeoff still has to be correct before the software multiplies anything. For contractors, the concrete slab cost for contractors must also account for local labor rates and crew productivity, which can vary widely by region.
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Add equipment, testing, and special inspection. Include the pump, laser screed, ride-on trowel, and any cylinder testing or special inspection required by the spec. Equipment that sits idle still costs money, so price standby separately. Also factor in the concrete mix design, since higher strengths or special admixtures can increase the concrete slab installation cost.
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Apply overhead and profit, then compare. Apply your overhead and profit to the direct cost, then divide the total by the slab area to get a unit cost. Compare that unit cost to your historical numbers for the same thickness and finish. If the two do not reconcile, find the difference before you bid. Running the numbers in estimating software is fast, but the labor rate, waste factor, and productivity assumptions still drive the answer.
Check the waste factor against your actual pour history. On small or irregular slabs, 5 percent is often too thin.
Common Mistakes in Concrete Slab Cost Estimating
- Forgetting the gravel base, vapor barrier or formwork. These items are not concrete, so they get dropped from the takeoff, yet a 4 in. compacted base, 10–15 mil vapor barrier and edge forms can add a meaningful share of the installed cost. Measure them separately.
- Using the wrong thickness or missing a thickened edge or grade beam. A slab that is 4 in. in the field but 12 in. at the perimeter is not one thickness. If you price the whole area at 4 in., the thickened edge, grade beam and any interior footings go unpaid.
- Not adding a waste factor, then running short on pour day. Ready-mix is ordered in full cubic yards, and short loads carry a penalty. A waste factor of roughly 5–10% covers spillage, uneven subgrade and over-excavation.
- Pricing reinforcement by area when it is actually priced by weight or by the bar. Rebar is bought and installed by the ton or by the linear foot per bar size. Converting a square-foot allowance to rebar without checking bar size, spacing and lap length understates the material and the tying labor.
- Ignoring pump, short-load or small-quantity charges. A pump truck, a minimum-load charge or a Saturday pour can swing the number more than the concrete itself on small slabs.
- Leaving out curing, sealing, saw cuts and joint filler. Curing compound, curing time, saw cutting within the window and joint filler are real line items. They are also the items most often cut when a bid is trimmed.
- Using a national average when local ready-mix prices differ by 30% or more. Aggregate, cement, haul distance and plant availability vary by market, so a national number can be far off. If you inherit someone else's estimate, run it through an estimate review before you rely on it. Also, remember that the concrete mix design affects both material cost and workability, which can impact the overall concrete slab installation cost.
Build a standard checklist for every slab takeoff: base, vapor barrier, formwork, concrete, reinforcement, placement, finishing, curing, joints and sealing. Walk it line by line before you total the sheet.
Concrete Slab Cost Calculator vs. Professional Takeoff
An online concrete slab cost calculator is useful for a quick ballpark on a simple rectangular slab with one thickness and one finish. Enter the length, width, thickness and a unit price, and you get a number in seconds. That is a reasonable first look for a shed pad or a short driveway.
It breaks down when the slab stops being a rectangle. Irregular shapes, multiple thicknesses, engineered reinforcement, grade beams, pump charges, phased pours and prevailing wage all sit outside what a simple calculator handles. A calculator also cannot see the drawings, so it misses thickened edges, dowels, keyways and construction joints that carry real cost.
A professional quantity takeoff measures from the actual drawings, applies local unit costs and shows the quantities behind every line. The result can be organized by CSI MasterFormat Division 03 — Concrete — so a general contractor or owner can compare bids line by line instead of comparing lump sums. For anything beyond a simple driveway or shed slab, a takeoff costs less than a wrong bid. If the slab is part of a larger structure, use concrete estimating services so the slab, foundations and reinforcement are priced together.
A calculator gives you a range. A takeoff gives you a bid. Know which one the moment calls for.
When to Get a Professional Concrete Slab Estimate
Get a professional concrete slab cost estimator involved when the slab is structural, when the reinforcement is engineered, when the project is bid competitively, or when the slab is part of a larger scope. Those are the situations where a missed thickened edge, dowel or pump charge turns a winning bid into a loss.
A professional estimate also pays for itself when you need a schedule of values, a price for a change order, or a second opinion on a subcontractor's number. A unit cost pulled from a national table rarely matches the ready-mix quote in your market, and a takeoff built from the drawings closes that gap.
Turnaround for a bid-ready takeoff is 24–48 hours for most projects, with rush available. Current offers include same-day quotes and 20% off. Start with concrete estimating services for slab and foundation scopes, bid estimating services when a hard bid is coming up, or upload your plans to get the number moving.
Send the drawings and the bid date. The scope of the takeoff follows the scope of the slab, not the size of the project.
Frequently asked questions
How much does a 30x30 concrete slab cost?
A 30 ft x 30 ft slab is 900 square feet. At a typical $6 to $14 per square foot for a 4-inch slab with mesh or rebar, that is roughly $5,400 to $12,600, plus sales tax. A 6-inch slab with heavier reinforcement, thicker edges or a commercial finish moves toward the upper end or above it. Site access, demolition, grading and whether you need a vapor barrier or thickened footings all change the number. Price your own thickness and reinforcement before you compare bids.
Is it cheaper to pour your own concrete slab?
Only if you already own the tools and can place and finish concrete correctly. Ready-mix is sold by the truckload, so a small pour may carry a short-load charge, and you still pay for forms, base material, reinforcement, curing and disposal. Poor finishing or wrong slump causes scaling, cracking and delamination that cost more to fix than the original pour. For anything larger than a small shed pad, the labor and risk usually favor a concrete subcontractor.
How many cubic yards of concrete do I need for a 20x20 slab?
A 20 ft x 20 ft slab is 400 square feet. At 4 inches thick, the volume is 400 x 0.333 ft = 133.3 cubic feet, divided by 27 = 4.94 cubic yards. At 6 inches thick it is 400 x 0.5 ft = 200 cubic feet, divided by 27 = 7.41 cubic yards. Add a waste and spillage allowance of about 5 to 10 percent, so order roughly 5.5 yards for the 4-inch slab and about 8 yards for the 6-inch slab.
What is the difference between a concrete slab cost per square foot and per cubic yard?
Cost per cubic yard prices the concrete material delivered to the site. Cost per square foot prices the finished slab, including base prep, forming, reinforcement, placing, finishing, curing and often overhead and profit. Because thickness links the two, a square-foot price is only meaningful when you state the thickness. Use the conversion 1 square foot at 4 inches thick equals about 0.0123 cubic yards, and at 6 inches about 0.0185 cubic yards.
Does a concrete slab cost more in winter?
It can. Cold weather requires heated water or aggregates, accelerating admixtures, insulated blankets and extended curing time, and some suppliers add a winter surcharge per cubic yard. Frozen subgrade must be thawed or removed before placement, and short daylight hours slow production. Hot weather brings its own costs through retarders, ice, shading and night pours. Ask your ready-mix supplier for seasonal surcharges and build them into the estimate rather than absorbing them.
How much does rebar add to a concrete slab cost?
Reinforcement is usually priced by weight or by area. A typical slab on grade uses #4 bars at 12 to 18 inches on center each way, which is roughly 0.7 to 1.0 pounds per square foot, plus chairs, tie wire and lap. At a material and install cost of roughly $1.00 to $2.00 per square foot, rebar often adds more than welded wire mesh, which is cheaper but provides less crack control. Heavier mats, dowels and thickened edges add more. See rebar estimating services for a quantity-based takeoff.
Can I use a concrete slab cost calculator for a commercial building?
A simple calculator works for a flat slab on grade with uniform thickness. Commercial work usually includes thickened edges, column pads, grade beams, slab depressions, trenches, vapor barriers, joint layout, dowels and specified finishes, none of which a basic calculator handles. Use one for a sanity check, then price from the drawings. A quantity takeoff tied to the structural sheets gives you a defensible number for a bid.
What is the average concrete slab cost per square meter in the U.S.?
Convert the square-foot range rather than quoting a separate market. One square meter equals 10.764 square feet. If a 4-inch slab costs $6 to $14 per square foot, that is roughly $65 to $150 per square meter for the same scope. Thickness, reinforcement and access drive the spread more than the unit you choose. State the thickness and currency whenever you quote a per-square-meter figure, because the number is meaningless without them.