The Concrete Calculator helps you calculate how many cubic yards of concrete you need for a slab. Simply fill in the fields above and click Calculate to get an instant result.
This calculator is part of Calculate Wiki’s Construction Calculators collection.
What You’ll Need
- Length (ft)
- Width (ft)
- Thickness (in)
- Waste Allowance (%)
Formula Used
Volume (ft³) = Length × Width × (Thickness in ÷ 12) × (1 + Waste %)
Cubic yards = Volume ÷ 27
Example Calculation
Using example inputs — Length = 10 ft; Width = 10 ft; Thickness = 4 in; Waste Allowance = 10 % — the Concrete Calculator returns:
| Value | Result |
|---|---|
| Volume | 36.7 ft³ (1.36 yd³) |
| 80 lb bags needed | 62 |
1.36 cubic yards. Or about 62 × 80 lb bags of pre-mix concrete.
Helpful Information
Results from the Concrete Calculator are estimates based on standard formulas used in the construction calculators field. For projects with significant cost, health, or safety implications, consider verifying results with a qualified professional.