Concrete Slab Cost Calculator
Pricing a slab or pad? Enter the size and thickness with your local concrete price to estimate the material cost, then add an optional installed price per square foot for a rough all-in figure. Material and installed estimates are shown separately — the installed number is your own input, not a contractor quote.
Total volume required
5.43Cubic Yards
Cubic feet
146.67
Cubic meters
4.15
Bags (80 lb)
245
Ready-mix cost
$869.14
Installed cost estimate (separate from material)
$3,200.00
400 sq ft × $8.00/sq ft. Not a contractor quote.
Estimate includes your waste factor. Figures are estimates, not a quote.
How to use this calculator
- 1Enter slab length, width, and thickness, plus a waste factor.
- 2Add your local ready-mix price per cubic yard for the material estimate.
- 3Optionally add an installed price per square foot (a typical poured-and-finished slab range is a few dollars to over ten per sq ft) for an all-in estimate.
- 4Read the material cost and the installed estimate as two separate lines.
Formula & rounding
Material cost = cubic yards × price per cubic yard. Installed estimate = slab area (length × width) × your installed price per square foot. The two are independent: the installed figure reflects whatever local quote you enter and never replaces a real bid.
20 ft × 20 ft slab, 4 inches, at $8/sq ft installed
- Slab area = 20 × 20 = 400 square feet
- Installed estimate = 400 × $8 = $3,200
- Material volume with 10% waste = 400 × (4 ÷ 12) × 1.10 = 146.7 cubic feet = 5.43 cubic yards
- Material cost at $160/yd³ ≈ 5.43 × $160 = $869
= ≈ $3,200 installed (or ≈ $869 material only)
4 in vs 6 in material cost, 20 ft × 20 ft slab
- 4 in: 400 × (4 ÷ 12) × 1.10 = 146.7 cu ft = 5.43 cubic yards → ≈ $869 at $160/yd³
- 6 in: 400 × (6 ÷ 12) × 1.10 = 220 cu ft = 8.15 cubic yards → ≈ $1,304 at $160/yd³
- A 6 in slab uses 50% more concrete than a 4 in slab of the same footprint
- Installed pricing usually rises too, since the thicker pour means more material and handling
= ≈ $869 (4 in) vs ≈ $1,304 (6 in) material — about $435 more
Slab cost snapshot by size (material vs installed)
Worked at 4 inches thick with a 10% waste factor, $160/yd³ material, and $8/sq ft installed — every value is editable in the calculator. The material and installed columns are independent, never added together.
| Slab size | Area | Concrete (4 in) | Material @ $160/yd³ | Installed @ $8/sq ft |
|---|---|---|---|---|
| 10 × 10 | 100 sq ft | 1.36 yd³ | ≈ $218 | ≈ $800 |
| 12 × 12 | 144 sq ft | 1.96 yd³ | ≈ $313 | ≈ $1,152 |
| 20 × 20 | 400 sq ft | 5.43 yd³ | ≈ $869 | ≈ $3,200 |
| 24 × 24 | 576 sq ft | 7.82 yd³ | ≈ $1,251 | ≈ $4,608 |
Estimate · unofficial. Installed price is the figure you enter, not a contractor bid; real quotes vary by finish, access, reinforcement, and region.
Frequently asked questions
How much does a concrete slab cost?
Installed slab cost is often quoted per square foot and depends on thickness, finish, site access, reinforcement, and region. Enter your local per-square-foot price for an estimate; for material alone, enter a price per cubic yard.
How much does a 20x20 concrete slab cost?
A 400 sq ft slab at, say, $8 per square foot installed is about $3,200. Material alone at 4 inches is roughly 5.4 cubic yards. Your real number depends on the quotes you enter.
Does a 4 inch vs 6 inch slab cost more?
A 6 inch slab uses 50% more concrete than a 4 inch slab of the same footprint, so material cost rises accordingly; installed pricing also tends to be higher. Change the thickness to compare.
What is the difference between material and installed cost?
Material cost is just the concrete. Installed cost adds labor, forms, reinforcement, finishing, and overhead. This tool shows material from your cubic-yard price and a separate installed estimate from your per-square-foot input.
Assumptions & sources
- Material cost
- cubic yards × your local price per yard (or bags × bag price), waste included.
- Installed estimate
- Optional $/sq ft you enter for a finished slab — regional, not a quote.
- Scope boundary
- Slab/pad specific; kept separate from the general cost calculator to avoid overlap.
- Waste factor
- Default 10% for spillage and sub-grade variation.
See the methodology & sources for how these values, formulas, and rounding are chosen.
Helpful concrete guides
- How to calculate concrete — covers the area, thickness, and waste-factor math behind the slab volume this tool prices.
This is an estimate, not a quote. Concrete quantities, bag yields, block coverage, and prices vary with product, brand, mix, region, supplier, tax, delivery, and on-site conditions. Always confirm with your supplier and round up for safety. For structural or code-related work, consult a qualified professional or your local building authority.