Concrete Calculator
Work out how much concrete you need for a slab, footing or column, and how many bags of cement, cubic metres of sand and aggregate that means for your chosen mix.
Your measurements
Estimate
- Concrete volume
- 3.15 m³
- Cement
- 26 bags (50 kg)
- Sand
- 1.32 m³
- Coarse aggregate
- 2.65 m³
Nominal mixes by volume. Structural work should follow the engineer's design mix.
Uses a dry-volume factor of 1.54 and 50 kg bags at 1440 kg/m³.
Common questions
How is concrete volume calculated?
Multiply length by width by thickness, all in metres, to get cubic metres. Add a wastage allowance for spillage and uneven sub-base, usually 3 to 10 percent.
Why is dry volume larger than wet volume?
Loose cement, sand and aggregate contain voids that fill when water is added and the mix is compacted, so roughly 54 percent more dry material is needed than the finished volume.