Concrete calculator
Work out how much concrete you need for a slab, path or base.
About this calculator
Enter the length, width and depth of the area. The calculator gives the volume in cubic metres, adds an allowance for waste, and estimates the weight and the number of 20 kg bags of mix.
Always order a little extra, since ground is never perfectly level.
Common questions
How much extra should I allow?
About 10% covers spills, uneven ground and settling.
How many bags make a cubic metre?
Roughly 110 bags of 20 kg mix, depending on the brand. Check the bag.
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