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Calixo

Concrete Calculator

Estimate the concrete volume and number of bags needed for a slab.

Inputs

Saved Scenarios

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Volume (m³)

1.50

25kg Bags Needed

120

Spark says

How it's calculated

Formula

Volume=Length×Width×DepthVolume = Length \times Width \times Depth
Length, Width
— Slab dimensions in metres
Depth
— Slab thickness in centimetres

What is the Concrete Calculator?

This calculator estimates the volume of concrete needed for a rectangular slab, and converts that to an approximate number of pre-mixed bags.

How to use it

  1. 1 Enter the slab length and width in metres.
  2. 2 Enter the slab depth in centimetres.

Worked examples

5m × 3m slab, 10cm deep

1.5 m³ of concrete, about 120 bags.

Try it

Limitations

  • •Bag yield varies by product and brand — check your specific bag's coverage for accurate quantities.
  • •Add 5-10% extra for waste and uneven ground on real projects.

Tips

  • 💡 For large pours, ready-mix delivered by the cubic metre is usually more economical than bags.

Frequently asked questions

How much concrete does one bag make?

A standard 25kg bag typically yields about 0.0125 m³ once mixed, but this varies by product — always check the manufacturer's coverage figures.