Concrete Mix Design (M20) Calculator

Work out concrete mix design (m20) instantly with clear inputs, formula shown and shareable results.

About Concrete Mix Design (M20) Calculator

M20 nominal mix is 1 part cement to 1.5 parts fine aggregate to 3 parts coarse aggregate by volume. Converting the dry volume split into mass uses bulk densities of 1440 kg/m³ for cement, 1600 for sand and 1450 for 20 mm aggregate, and water follows from the chosen water-cement ratio applied to the cement mass.

Formulas

Material masses

Cement kg = dry volume / 5.5 x 1440; sand and aggregate follow their parts and bulk densities

Water

Litres = cement kg x water-cement ratio

Worked example

With the default values below, Concrete Mix Design (M20) Calculator returns Cement required of 4,032. Change any input above and every figure here is recalculated in your browser.

Inputs used

Concrete volumeminimum 0.01 m³: 10 m³
Water-cement ratioaccepts 0.3–0.7: 0.5
Dry volume factoraccepts 1–2: 1.54

Results

Cement required: 4,032 kg
Fine aggregate: 6,720 kg
Coarse aggregate: 12,180 kg
Water required: 2,016.0 L

Step by step

1Values used
2Material masses
3Water
4Cement required= 4,032 kg
5Fine aggregate= 6,720 kg
6Coarse aggregate= 12,180 kg
7Water required= 2,016.0 L

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Structural concrete requires a designed mix, trial batches and cube testing to the applicable standard.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Structural concrete requires a designed mix, trial batches and cube testing to the applicable standard.

Frequently Asked Questions

How is the Concrete Mix Design (M20) figure worked out?

Cement kg = dry volume / 5.5 x 1440; sand and aggregate follow their parts and bulk densities. M20 nominal mix is 1 part cement to 1.5 parts fine aggregate to 3 parts coarse aggregate by volume.

Is a nominal mix acceptable for structural work?

Only for small or non-critical elements. Codes require design mixes with trial batches and cube testing for structural concrete above modest grades.

What values do I need to enter?

This calculator takes 3 inputs: Concrete volume, Water-cement ratio, Dry volume factor. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.