Method
Wet concrete shrinks as voids fill, so dry material volume is taken as 1.54 × wet volume. That dry volume is split in the mix ratio. One 50 kg bag of cement is 0.0347 m³.
- M10: 1 : 3 : 6
- M15: 1 : 2 : 4
- M20: 1 : 1.5 : 3
- M25: 1 : 1 : 2
Example
1 m³ of M20 concrete needs about 8.1 bags of cement, 0.42 m³ of sand and 0.84 m³ of 20 mm aggregate.
Frequently asked questions
How many bags of cement are in 1 m³ of M20?
About 8 bags with nominal mix. Design mixes from a ready-mix plant may use 7–8 bags.
How do I convert cu ft to m³?
Divide by 35.31. The calculator accepts either unit.
Why is the water-cement ratio important?
Too much water weakens concrete. Around 0.45–0.5 is typical for M20.
Sources
- Bureau of Indian Standards ↗ – IS 456 nominal concrete mixes
- ICE embodied carbon database (Circular Ecology) ↗ – carbon per kg of each material