Concrete Calculator
Estimate how much concrete you need for a slab, footing or column. Enter the dimensions in metric or imperial units and the calculator reports the volume in cubic yards or cubic metres, plus the number of standard bags.
Enter slab, footing or column dimensions
Enter dimensions, then press Calculate concrete.
Concrete volume formulas
Slab: V = length × width × thickness
Column: V = π × (diameter/2)² × height
Common bag yields
| Bag size | Volume (cubic feet) | Volume (cubic metres) |
|---|---|---|
| 40 lb | 0.30 ft³ | 0.0085 m³ |
| 60 lb | 0.45 ft³ | 0.0127 m³ |
| 80 lb | 0.60 ft³ | 0.0170 m³ |
Metric ↔ Imperial conversions
1 cubic metre ≈ 1.30795 cubic yards. 1 cubic yard = 27 cubic feet.
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Frequently asked questions
A typical 80 lb bag of concrete mix yields about 0.6 cubic feet (0.017 m³). A 60 lb bag yields 0.45 ft³ and a 40 lb bag yields 0.30 ft³. Yields can vary slightly by manufacturer.
Yes — always add 5–10% to cover spillage, uneven subgrade and small measurement errors. Ordering short is expensive; ordering slightly extra is cheap insurance.