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Cement calculator

Estimate how much cement, sand and aggregate you need for a volume of concrete, based on a standard mix ratio.

How it works Report a problem

Cement calculator

Enter your values below and press Calculate to see your result instantly.

Required Cement Bags (50kg)
63 Bags
SAND VOLUME
4.4 m³
AGGREGATE VOLUME
8.8 m³
Total Dry Volume is calculated at 15.4 m³ (including 54% wastage/shrinkage factor).

About the Cement calculator

Estimate how much cement, sand and aggregate you need for a volume of concrete, based on a standard mix ratio.

How to use the Cement calculator

  1. Enter the Total Concrete Volume (m³).
  2. Choose the Mix Ratio (C:S:A): M10, M15, M20 or M25.
  3. Press Calculate Materials.

Formula and method

Dry volume is about 1.54 times the wet volume to allow for voids. Each material's share is its part of the ratio divided by the sum of the parts. Cement is converted to weight (about 1,440 kg/m³) and to 50 kg bags.

Worked example

1 m³ of M20 concrete (1 : 1.5 : 3): dry volume 1.54 m³, cement share 1 ÷ 5.5, giving about 403 kg of cement (about 8 bags), plus sand and aggregate.

Tips

  • Add 5 to 10 percent for waste.
  • Follow your engineer's specification for structural work.

Frequently asked questions

What does M20 mean?
The grade of concrete with a target compressive strength of 20 MPa after 28 days.