Concrete mix calculator: cement, sand, aggregate
Enter the wet concrete volume and pick a mix ratio to see each material by the common volume-batching method used in quantity surveying.
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How to use it
- Enter concrete volume, mix ratio (cement:sand:aggregate), dry volume factor, cement bulk density and cement bag weight.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Dry volume = wet volume × dry volume factor (1.54). Cement volume = dry volume × (1 ÷ sum of parts); weight = volume × cement bulk density (1440 kg/m³). Sand and aggregate use their own parts.
Example
Inputs: Concrete volume = 1 m³, Mix ratio (cement:sand:aggregate) = 1:2:4 (about M15), Dry volume factor = 1.54, Cement bulk density = 1,440 kg/m³, Cement bag weight = 50 kg. Result: Cement bags to buy: 7 bags; Cement weight: 316.8 kg; Sand: 0.44 m³.
Limits and caveats
- Volume batching is approximate; structural concrete is designed by weight and tested by an engineer.
- The 1.54 factor and 1440 kg/m³ are common estimating values and you can change them.
- Water is not calculated because it depends on sand moisture and the workability needed.
Questions about this tool
How many cement bags for 1 m³ of 1:2:4 concrete?
About 6.34 bags of 50 kg, so 7 to buy, with 0.44 m³ of sand and 0.88 m³ of aggregate.
What does the 1.54 dry volume factor mean?
Dry materials shrink when water is added and fill voids, so about 1.54 m³ of dry materials make 1 m³ of concrete.
Which ratio for footings and slabs?
1:1.5:3 is common for light structural work and 1:3:6 for blinding, but structural jobs follow the mix design set by the engineer.