Estimate the concrete for a slab, base or footing. Enter the length, width and depth and the calculator returns the volume in cubic metres, plus a rough count of 25 kg bags. Add a little extra for uneven ground and spillage. Beyond about a cubic metre, ordering ready-mix is usually more economical than mixing bags by hand.
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Frequently asked questions
How many bags of concrete per cubic metre?
Roughly 90 to 110 bags of 25 kg mix per cubic metre, depending on the product. This is why ready-mix is far more practical for larger pours.
Should I add extra?
Yes — allow around 5 to 10 percent extra for uneven sub-base, spillage and over-dig, so you do not run short mid-pour.