Concrete Slab Calculator
Work out how much concrete you need for a rectangular concrete slab, including a waste allowance.
For slabs, strip footings, trenches and walls with rectangular dimensions.
Concrete calculator for different shapes
This calculator handles common concrete jobs rather than assuming every pour is a rectangular slab. It converts each measurement to metres internally, calculates the shape volume, multiplies by the number of identical pours, then applies your chosen allowance.
You can mix units. For example, you can enter a slab length in metres, a width in feet and a thickness in millimetres.
What it calculates
Rectangular slabs, strip footings, trenches, walls, circular pads, round and rectangular columns, hollow round columns, ring footings, triangular sections, trapezoidal sections and stepped pours are supported.
Concrete quantities are estimates. Actual ordering should allow for excavation tolerances, uneven ground, spillage, pumping losses and the supplier's delivery increments.