m³

Concrete Calculator

The concrete for a slab or round columns, in cubic metres or yards and in premix bags.

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Result…

Units
Pour
m
m
cm
%

5–10% covers spillage and an uneven base.

m³ per 20 kg bag

Printed on the bag; a 20 kg bag makes about 0.009 m³, a 60 lb bag about 0.45 ft³.

 

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How it's calculated

Slab = length × width × thickness
Column = π × (diameter ÷ 2)² × height
Bags = volume ÷ bag yield, rounded up
1 cubic yard = 27 ft³

Works out how much concrete to order for a flat slab or for round columns and post holes, with an allowance for spillage. Premix bags are counted from the yield printed on the bag (a 20 kg bag makes about 0.009 m³, a 60 lb bag about 0.45 ft³). Large pours are usually ordered as ready-mix by the cubic metre or yard.

Your numbers, step by step

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