How to Calculate Concrete for a Slab
Multiply Length × Width × (Thickness÷12) to get cubic feet. Divide by 27 to get cubic yards. Add 10% for waste.
How Much Does Concrete Cost?
Ready-mix: $115–$150/cubic yard delivered. Bags: $4.50–$5.50 per 60-lb bag. A 20×15ft slab (4in thick) costs ~$285–$370.
Common Slab Thicknesses
Sidewalk: 4in • Patio: 4in • Driveway: 5–6in • Garage: 6in • Foundation: 8–12in
How to Calculate Concrete Slab
Use this free concrete slab calculator to get instant, accurate results for your construction project. Simply enter your measurements above and the calculator will automatically compute the result using industry-standard formulas.
Pro Tip: Always add 10-15% extra material to account for waste, cuts, and job-site conditions. This is standard practice recommended by experienced contractors.