Concrete Slab Calculator
Calculate how much concrete you need for a patio, driveway, garage floor, or sidewalk slab.
Project type
ft
ft
in
#
Waste factor:
Quick-select presetsAdjustable waste factorImperial & metricNo signup required
How to Calculate Concrete for a Slab
Slab Volume Formula
Volume = Length (ft) × Width (ft) × Thickness (in) ÷ 12 ÷ 27 = Cubic Yards
Multiply your slab's length and width in feet, then multiply by the thickness converted from inches to feet (divide inches by 12). Divide the total by 27 to convert cubic feet to cubic yards.
Recommended Slab Thickness by Project
| Project | Thickness | Notes |
|---|---|---|
| Patio | 4 inches | Standard for foot traffic |
| Sidewalk | 4 inches | Residential standard |
| Driveway | 5–6 inches | Must support vehicles |
| Garage floor | 6 inches | Heavy loads, vehicles |
| Shed foundation | 4–6 inches | Depends on shed size |
Concrete Slab Calculator — Examples
Concrete for a 10×10 Patio Slab
10 ft × 10 ft × 4" thick = 33.33 cu ft ÷ 27
Result: 1.24 cubic yards (1.36 with 10% waste)
Concrete for a 20×20 Driveway
20 ft × 20 ft × 5" thick = 166.67 cu ft ÷ 27
Result: 6.17 cubic yards (6.79 with 10% waste)
Concrete for a 24×24 Garage Slab
24 ft × 24 ft × 6" thick = 288 cu ft ÷ 27
Result: 10.67 cubic yards (11.73 with 10% waste)
Why Use MaterialCalc's Slab Calculator?
Project type presets
Adjustable waste factor
Imperial & metric
Multiple slab support
Bag estimate included
Free, no signup