Concrete Calculator
Work out the volume of concrete needed for a slab, footing or post from its dimensions.
Ordering the right amount of concrete
Concrete is bought by volume, so a pour comes down to working out the cubic measure of the space you are filling from its dimensions. This calculates that volume, so you can order or mix the right amount for a slab, a footing, or a set of post holes.
Enter the dimensions to see the volume of concrete required.
Running short is the disaster
With concrete, being a bit over is a minor waste; being short is a genuine problem, because a pour needs to be continuous — if you run out partway, the join between the old and new concrete is weak and visible. So the sensible practice is to round up and add a small margin, and to account for the ground not being perfectly level, which quietly increases the volume. Getting the calculation right, then ordering slightly generously, avoids the far worse outcome of a half-finished pour.
Concrete Calculator FAQ
Why add a margin to the concrete volume?
Because a pour must be continuous — running short leaves a weak join. It is safer to have a little spare than to run out mid-pour.
What shapes can it handle?
Slabs, footings and post holes — the common pours — calculated from their dimensions.
Is anything uploaded?
No. The calculation happens in your browser.