Concrete Calculator
Calculate exact concrete volume for slabs, footings, columns, and round piers in cubic yards, cubic feet, and cubic meters, including premix bag estimates.
Last verified: September 2026Inputs & Parameters
Calculation Results
Estimated volume includes a 10% contingency buffer for ground unevenness, spillage, and slab deflection.
Concrete Volume & Bag Estimation Methodology
Concrete volume calculations determine the physical 3-dimensional space required for standard geometric pours, converting measurements into standard delivery units: Cubic Yards (yd³) for imperial projects or Cubic Meters (m³) for metric specifications.
Volume Geometric Formulas
- Slab / Footing (Rectangular Prism):
Volume = Length × Width × Thickness - Column / Pier (Cylinder):
Volume = π × (Diameter / 2)² × Depth - Cubic Yards Conversion:
Cubic Yards = Cubic Feet / 27
Recommended Waste Allowance
Construction industry best practices recommend budgeting an additional 5% to 10% over theoretical volume to account for subgrade unevenness, formwork deflection, spillage, and settling.
Premix Bag Coverage Estimates
For small pours where ready-mix truck delivery is uneconomical, pre-blended dry concrete bags are standard:
| Bag Size | Yield per Bag (cu ft) | Yield per Bag (cu yd) | Bags per Cubic Yard |
|---|---|---|---|
| 80 lb Bag | 0.60 ft³ | 0.022 yd³ | 45 bags |
| 60 lb Bag | 0.45 ft³ | 0.017 yd³ | 60 bags |
| 50 lb Bag | 0.375 ft³ | 0.014 yd³ | 72 bags |