Concrete Calculator
Calculate concrete volume for slabs, columns, and footings in m³ or yd³.
Add 10% waste allowance to bag counts for real projects.
How concrete volume is calculated
For slabs and footings, volume = length × width × depth. For cylindrical columns, volume = π × radius² × height. All dimensions are converted to metres before calculation. The result is also shown in cubic yards and expressed as the number of pre-mixed bags (40 lb bags yield ~0.0095 m³; 80 lb bags yield ~0.019 m³).
Frequently asked questions
Should I add extra for wastage?
Yes — add 10% to your final volume for wastage from spillage, uneven sub-base, and over-pour. The calculator shows the net volume; always order slightly more than the exact calculation.
When should I order ready-mix instead of bags?
Pre-mixed bags are cost-effective for small pours under 1 m³. For larger slabs or structural work, ready-mix concrete (delivered by truck) is cheaper per m³ and more consistent. The crossover point is typically 1–2 m³.
