Concrete is one of the most widely used materials in civil engineering. It is composed of four main ingredients: cement, sand, coarse aggregate, and water.
Accurate calculation of these materials ensures proper mix proportioning, precise cost estimation, and effective quality control on-site.
Understanding Concrete Mix Ratio
A mix ratio defines the proportion of each material by volume.
For example, a 1 : 1.5 : 3 mix means:
| Material | Proportion |
|---|---|
| Cement | 1 part |
| Sand (Fine Aggregate) | 1.5 parts |
| Coarse Aggregate | 3 parts |
Step-by-Step Calculation for 1 m³ Concrete (1 : 1.5 : 3 Mix)
Data
Concrete ratio = 1:1.5:3
Concrete volume = 1 cum
As we know the Volume of dry Concrete = is 1.55 to 1.57 times the volume of wet concrete
So total volume of required concrete will be= 1 x 1.56=1.56 cum (Assume factor as 1.56)
Calculation
Concrete Ratio = 1: 1.5: 3 Means;
Cement is in ratio 1
Fine sand is in a ratio 1.5
And coarse aggregate is in ratio 3
So total ratio will be = 1+1.5+3 = 5.5
Quantity of Cement
Quantity of Cement = Ratio of cement x volume of dry concrete / Total ratio
= 1 x 1.56 / 5.5
=0.284 cum
Unit weight of cement = 1400 ~ 1500 kg/cum (Assume 1450kg/cum)
1cum of cement = 1450kg
Quantity of cement= 0.284 x 1450 = 412kg
1 cement beg = 50 kg
No of cement begs required = 412 / 50 =8.24 ~ 8 begs
Quantity of Fine sand
Quantity of fine sand = Ratio of fine sand x volume of dry concrete / Total ratio
= 1.5 x 1.56 / 5.5
=0.425 cum
Unit weight of Fine sand = 1600 ~ 1800 kg/cum (Assume 1700 kg/cum)
Quantity of Fine sand= 0.425 x 1700 =722.5 kg
Quantity of Coarse aggregates
Quantity of coarse aggregate = Ratio of coarse aggregates x volume of dry concrete / Total ratio
= 3 x 1.56 / 5.5
=0.851 cum
Unit weight of coarse aggregate = 1500 ~ 1800 kg/cum (Assume 1650 kg/cum)
Quantity of coarse aggregates= 0.851 x 1650 =1404 kg
Amount of Water Required
The water-cement ratio depends upon the strength, climatic factors, and workability requirement of concrete.
Cement required for 1 cum of concrete = 412Kg
Assume w/c ratio = 0.50 Water required for 1 cum of concrete. = 412 x 0.5
Amount of Water Required for 1 cum of concrete = 206 kg = 206 liters
Summary
So, for a 1 cum 1:1.5:3 concrete, we would need approximately:
- 8 bags of cement
- 0.425 cum of fine sand
- 0.851 cum of coarse aggregate
- 206 liters of water
Note: Please note that this calculation is approximate and can vary depending on the properties of the used materials and applicable standards in the specific region.
Key Notes and Best Practices
- Use actual densities from your supplier or lab for better accuracy.
- Adjust w/c ratio based on the required strength and slump test results.
- Avoid over-watering, as it weakens the concrete and causes segregation.
- Round up cement bags — never use fractions on site.
- Add 2–5 % extra to cover spillage and wastage.
- For structural projects, always confirm proportions with a design mix.
Automatic Calculation
Use the calculator below to automatically estimate the quantities of materials required for concrete.
Simply enter your desired values, and the results will be generated instantly.
In the mix ratio field, enter your concrete design proportion — for example, 1:1.5:3, 1:2:4, or any other mix as needed.
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