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# Concrete Ingredients Calculator metric

These Concrete Calculators work out the required cement and all-in ballast or cement, sharp sand and gravel required to complete a user defined volume of finished concrete. Both concrete calculators make an allowance for the fact that ballast etc losses volume when mixed to make concrete.

Two Concrete Calculator are provided for different concrete mixes:

1. General mix - 1:5 cement:all-in ballast or 1:2½:3½ cement:sharp sand:gravel.
and
2. Paving mix - 1:3½ cement:all-in ballast or 1:1½:2½ cement:sharp sand:gravel.
Comment: If you are wondering how 1:2½:3½ equals 1:5 ("shouldn't it be 1:6" I hear someone say), the answer is that there is a lot of space between the individual pieces of gravel which will accommodate some sand, and when 2½ parts sand is mixed with 3½ parts gravel, the final volume will reduce down to about 5 parts.

## General mix - 1:5 or 1:2½:3½

 Enter the finished volume of the work space: cubic metres Note: this calculator includes an allowance for the concrete 'shrinkage' You will need approximately:- Portland cement tonne 50kg bags Sharp sand tonne cubic metres Gravel - 20mm tonne cubic metres OR Ballast - 20mm tonne cubic metres

## Paving mix - 1:3½ or 1:1½:2½

 Enter the finished volume of the work space: cubic metres Note: this calculator includes an allowance for the concrete 'shrinkage' You will need approximately:- Portland cement tonne 50kg bags Sharp sand tonne cubic metres Gravel - 20mm tonne cubic metres OR Ballast - 20mm tonne cubic metres