Concrete Slab Cost Calculator
Planning a concrete driveway, patio, or foundation? Our concrete slab cost calculator estimates the total project cost including materials, labor, reinforcement, and forms. Enter your slab dimensions and thickness to see how many cubic yards of concrete you need and what you can expect to pay. Whether you're hiring a contractor or doing it yourself, understanding the full cost breakdown helps you budget accurately and evaluate quotes from professionals.
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4" for patios, 5-6" for driveways
Ready-mix delivery typically $120-180/yd
Standard broom finish ~$2.50-3.50/sq ft; decorative, reinforced, or high-cost regions run higher
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How much does a concrete slab cost?
The cost of a concrete slab depends on its size, its thickness, and your local ready-mix price. At this calculator's defaults a 4 inch slab runs about $6.30 to $6.85 per square foot installed, which covers the ready-mix concrete, finishing labor, wire mesh, and form boards. The concrete material by itself is a much smaller share of that total, usually $1.50 to $2.50 per square foot, so a DIY pour where you supply the labor costs far less than a full contractor install.
Use the calculator above for your exact dimensions and local price, then compare any concrete slab price you are quoted against the size table below. The figures come straight from the same math, so they are a quick way to sanity check a bid before you call a contractor.
Concrete slab cost by size
The table shows the estimated installed cost for common slab sizes at 4 inches thick. Each cost is a range that reflects ready-mix concrete priced from $120 to $180 per cubic yard, with the calculator's $150 default sitting in the middle. Every figure also includes the calculator's default $3.50 per square foot finishing labor, $0.50 per square foot wire mesh, $2 per linear foot for forms, and a 10 percent waste factor. These are full contractor install estimates for a standard broom finish; costs vary by region, and reinforcement or decorative finishes cost more. You can raise the labor rate in the calculator for a premium install.
| Slab size | Square feet | Cubic yards (4 in) | Estimated installed cost |
|---|---|---|---|
| 10 x 10 | 100 | 1.4 | $643 to $724 |
| 12 x 12 | 144 | 2.0 | $907 to $1,024 |
| 16 x 20 | 320 | 4.3 | $1,945 to $2,206 |
| 20 x 30 | 600 | 8.1 | $3,578 to $4,067 |
| 24 x 24 | 576 | 7.8 | $3,435 to $3,904 |
| 30 x 30 | 900 | 12.2 | $5,307 to $6,040 |
At the default $150 per cubic yard the calculator returns $684, $965, $2,076, $3,822, $3,669, and $5,673 for these sizes, which is the number you get by entering the same dimensions in the tool above. A 30x30 concrete slab cost lands near $5,673 installed, while the ready-mix concrete alone is about $1,500 to $2,200.
What goes into concrete slab installation cost
Concrete slab installation cost is more than the concrete. Four line items drive the total, and the calculator estimates each one.
- Concrete material: Ready-mix delivery runs $120 to $180 per cubic yard. One cubic yard covers about 81 square feet at 4 inches, 65 square feet at 5 inches, and 54 square feet at 6 inches, so a thicker pour raises the material cost.
- Concrete labor cost: Finishing labor for a standard broom-finished slab runs about $2.50 to $3.50 per square foot, and the calculator defaults to $3.50. It is the line that varies most by region, and premium or decorative finishes run higher, so you can adjust the labor rate in the calculator.
- Reinforcement: Wire mesh at $0.50 per square foot, or rebar for driveways and heavier loads, controls cracking.
- Forms: Form boards at $2 per linear foot of perimeter shape the pour.
A plain concrete pad cost for a shed or an AC unit follows the same math at a smaller size, while a concrete slab foundation cost runs higher once you add thickness, rebar, and a deeper footing. The calculator does not include excavation or base prep, which a contractor bills separately.
How many bags of concrete do I need?
For small pours you may skip ready-mix and use bagged concrete instead. Working out how many bags of concrete do I need comes down to volume: a 60 pound bag yields about 0.45 cubic feet and an 80 pound bag about 0.60 cubic feet. A 10 by 10 foot slab at 4 inches needs roughly 62 bags of 80 pound concrete or 82 bags of 60 pound concrete with a 10 percent waste allowance. Above about 1 cubic yard, ready-mix delivery is cheaper and faster than mixing bags by hand, which is why the cost estimates above assume ready-mix. To price the bag route for your size, the concrete bag calculator gives an exact count by bag weight.
How It's Calculated
1. Volume (cu ft) = Length × Width × (Thickness ÷ 12) 2. Cubic Yards = Volume ÷ 27 3. Total Needed = Cubic Yards × (1 + Waste Factor) 4. Material Cost = Total Needed × Price per Yard 5. Labor = Square Feet × Labor Rate (default $3.50 per sq ft) 6. Reinforcement = Square Feet × $0.50 7. Forms = Perimeter × $2 per linear ft 8. Slab Weight = Volume (cu ft) × 133 lbs/ft³ 9. 60-lb Bag Equivalent = Total Volume (with waste) ÷ 0.45 cu ft/bag (rounded up) 10. 80-lb Bag Equivalent = Total Volume (with waste) ÷ 0.60 cu ft/bag (rounded up) Total = Material + Labor + Reinforcement + Forms
Worked Examples
A 40×20 foot driveway at 5" thick: Volume = 40×20×0.417 = 333 cu ft = 12.3 cu yd. With 10% waste = 13.6 cu yd (~$2,040 for concrete). Total installed with labor, mesh, and forms: about $5,477.
A 16×12 foot patio at 4" thick: Volume = 16×12×0.333 = 64 cu ft = 2.4 cu yd. With waste = 2.6 cu yd (~$390 for concrete). Total installed: about $1,271.
A 24×24 foot garage floor at 4" thick: Volume = 576 × 0.333 = 192 cu ft = 7.1 cu yd. With waste = 7.8 cu yd (~$1,170 for concrete). Total installed: about $3,669.
Assumptions & Waste Factor
- Ready-mix concrete delivery (not bagged concrete)
- Standard 3,000-4,000 PSI residential concrete
- Finishing labor defaults to $3.50 per square foot (adjustable); decorative or heavily reinforced work and high-cost regions run higher
- Wire mesh reinforcement at $0.50 per sq ft
- Form boards at $2 per linear foot of perimeter
- Concrete density of 133 lbs/ft³ (≈2,130 kg/m³) for weight calculation
- Bag equivalents based on ready-mix volume. For actual bagged-concrete projects use the Concrete Bag Calculator
- Does not include excavation or base prep costs
Standard waste factor is 10% for most concrete work. Irregular shapes or uneven ground may require 15%. Extra material ensures you don't run short during the pour since you can't stop midway.
Frequently Asked Questions
How much does a concrete slab cost?
At this calculator's defaults a 4-inch concrete slab runs about $6.30 to $6.85 per square foot installed, covering ready-mix concrete, finishing labor, wire mesh, and forms. For example, a 12 by 12 foot patio is about $965 and a 20 by 30 foot slab about $3,822 at $150 per cubic yard. Costs vary by region, and reinforcement or decorative finishes cost more. The concrete material alone is a much smaller share, so a DIY pour costs far less than a full contractor install.
How much does a 30x30 concrete slab cost?
A 30 by 30 foot slab is 900 square feet and needs about 12.2 cubic yards of concrete at 4 inches thick. At the default $150 per cubic yard the full installed estimate is about $5,673, or roughly $5,307 to $6,040 across the $120 to $180 per cubic yard range. The ready-mix concrete by itself is about $1,500 to $2,200, with the rest going to labor, wire mesh, and forms. Reinforcement, decorative finishes, and high-cost regions run higher.
How much does concrete labor cost?
Concrete finishing labor for a standard broom-finished slab commonly runs about $2.50 to $3.50 per square foot, and this calculator defaults to $3.50. On a 400 square foot slab that is about $1,400 of the total cost. Premium, decorative, or heavily reinforced installs and high-cost regions run higher, and you can raise the labor rate in the calculator. Excavation and base prep are billed separately.
How many bags of concrete do I need for a slab?
It depends on the slab size and the bag you buy. A 60 pound bag yields about 0.45 cubic feet and an 80 pound bag about 0.60 cubic feet. A 10 by 10 foot slab at 4 inches needs roughly 62 bags of 80 pound concrete or 82 bags of 60 pound concrete with a 10 percent waste allowance. Above about 1 cubic yard, ready-mix delivery is cheaper. For an exact bag count, use the concrete bag calculator.
How thick should my concrete slab be?
Patios and walkways: 4 inches. Standard driveways: 5 inches. Heavy vehicle driveways: 6 inches. Garage floors: 4-6 inches. Always pour on a compacted gravel base for proper drainage and support.
How much does ready-mix concrete cost?
Ready-mix concrete costs $120-180 per cubic yard delivered, depending on your location and the mix specifications. There's typically a minimum delivery charge (usually 1 yard) and possible extra fees for small loads.
Should I use ready-mix or bagged concrete?
Use ready-mix for anything over 1 cubic yard since it's more economical and ensures consistent quality. Bagged concrete works for small projects like post holes or small repairs, but is labor-intensive for larger pours.
Do I need rebar or wire mesh?
Wire mesh or fiber reinforcement is sufficient for most residential slabs. Rebar is recommended for driveways, areas with heavy loads, or where soil conditions are poor. Reinforcement prevents cracking and extends slab life.
Can I pour concrete myself?
Small projects are DIY-friendly if you have help and proper tools. Larger pours require experience because concrete sets quickly and mistakes are permanent. For driveways and large patios, hiring professionals is usually worth the cost.
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Disclaimer: This calculator provides estimates for planning purposes only. Actual material requirements may vary based on site conditions, installation methods, and other factors. Always consult with a qualified professional before making purchasing decisions.