How is the concrete volume calculated?

It multiplies length by width by depth (converting depth into the same unit) to give the volume in cubic metres or cubic feet, then divides by the yield per bag and rounds up.

What yield should I enter per bag?

A standard 25 kg bag yields roughly 0.011 m³ (about 0.4 ft³) of mixed concrete; a 20 kg bag yields slightly less. Check the bag for the exact figure. The default is 0.011 m³.

Is my data sent anywhere?

No. Every calculation runs entirely in your browser and nothing is uploaded to any server.

Concrete Calculator

Concrete volume and number of bags for a slab or footing.

Concrete calculator — volume and bags

Estimate the volume of concrete for a slab, path or footing and how many bags of mix to buy. Enter the length, width and depth, set the yield per bag printed on the packaging, and the calculator returns both the cubic volume and the bag count.

It multiplies the dimensions into a volume, divides by the bag yield, and rounds up to whole bags — all computed instantly in your browser.