Concrete Slab Cost Formulas
\(\text{Thickness (ft)} = \frac{\text{Thickness (in)}}{12}\) \(\text{Volume (cu yd)} = \frac{\text{Area (sq ft)} \times \text{Thickness (ft)}}{27} \times 1.10 \quad \text{(with 10\% waste)}\) \(\text{Material Cost} = \text{Volume (cu yd)} \times \text{Cost Per Yard}\) \(\text{Labor Cost} = \text{Area (sq ft)} \times \text{Labor Rate Per Sq Ft}\) \(\text{Total Project Cost} = \text{Material Cost} + \text{Labor Cost}\)
Installed Concrete Slab Cost Table ($135/yd Concrete, $5.50/sq ft Labor)
| Slab Size & Area | Slab Thickness | Concrete Volume (+10%) | Material Cost | Labor Cost | Total Installed Cost | Installed Cost / Sq Ft |
|---|---|---|---|---|---|---|
| 10 ft × 10 ft (100 sq ft) | 4 inches | 1.36 cu yds | $183.60 | $550.00 | $733.60 | $7.34 / sq ft |
| 12 ft × 20 ft (240 sq ft) | 4 inches | 3.26 cu yds | $440.10 | $1,320.00 | $1,760.10 | $7.33 / sq ft |
| 20 ft × 20 ft (400 sq ft) | 4 inches | 5.43 cu yds | $733.05 | $2,200.00 | $2,933.05 | $7.33 / sq ft |
| 24 ft × 24 ft (576 sq ft) | 6 inches (Driveway) | 11.73 cu yds | $1,583.55 | $3,168.00 | $4,751.55 | $8.25 / sq ft |
How to Use This Concrete Slab Cost Calculator
- Select your preferred account currency from the header picker.
- Enter total slab area in square feet (e.g., 400 sq ft).
- Input slab thickness in inches (4 in for patio, 6 in for driveway).
- Enter concrete cost per cubic yard (national avg ~$135/yd).
- Specify contractor labor rate per square foot (avg ~$5.50/sq ft).
- View total installed project cost, cost per sq ft, and material vs labor breakdown.
Frequently Asked Questions
How much does a 20x20 concrete slab cost?
A 20x20 concrete slab (400 sq ft, 4 inches thick) typically costs between $2,400 and $4,400 installed ($6 to $11 per sq ft), depending on labor and site preparation.
What is the average cost per square foot for pouring a concrete slab?
The national average cost for an installed concrete slab ranges from $6.00 to $12.00 per square foot, including site excavation, rebar mesh, forms, concrete, and finishing labor.
How many cubic yards of concrete are needed for a 400 sq ft slab?
A 400 sq ft slab at 4 inches thickness requires approximately 4.94 cubic yards of concrete (including a 10% waste factor).
What factors increase concrete slab installation costs?
Costs increase with thicker slabs (6 inches vs 4 inches), stamped/colored finishes, site grading, pump truck rental, and heavy rebar reinforcement.
How does slab thickness affect total cost?
Increasing slab thickness from 4 inches to 6 inches increases concrete volume (and material cost) by 50%.
Is DIY pouring cheaper than hiring a contractor?
DIY saves labor ($3 to $7/sq ft), but requires building forms, ordering ready-mix or mixing 50+ heavy bags, leveling, screeding, and floating before concrete sets.
Is my personal data stored anywhere?
No. All calculations run locally in your web browser.