Calculate Concrete Volume and Bags

Volume is area times depth. For a slab or footing it is length × width × thickness; for a round column it is π × radius² × height. The calculator does this and adds your waste margin.

It depends on the bag size. This tool assumes a 25 kg pre-mix bag that yields about 0.0125 m³. For large pours, ready-mix delivered by truck is usually cheaper than bags.

Some concrete is always lost to spillage, uneven sub-grade and over-excavated holes. A 5–10% margin helps you avoid running short mid-pour, which leaves a cold joint.

A cubic yard is the common ordering unit for ready-mix concrete in North America and equals about 0.765 cubic metres. The calculator shows both so you can order in either unit.