How much concrete do I need?

For a rectangular slab, multiply length, width, and depth in meters. Add an allowance appropriate to the project.

Worked example

A 5 m × 4 m slab at 150 mm depth needs 3 m³ before waste. A 10% allowance gives 3.3 m³. Confirm dimensions, supplier rounding, and site conditions.

Try it with your own numbers

Use the Concrete Calculator to check another example. Read the input labels carefully and keep units consistent.

Before you use the answer

Choose the correct starting quantity and keep full precision until the final step. An arithmetic result describes the numbers entered; the usefulness of the result depends on accurate measurements and the assumptions in the calculation.