Cement Concrete Calculator
Frequently asked
How many cement bags are needed per cubic metre of M20 concrete?
About 8 bags (403 kg) of cement per cubic metre of finished M20 (1:1.5:3) concrete, after applying the 1.54 dry-volume factor. This calculator computes the exact figure for your dimensions and grade.
Why is dry volume 1.54 times the wet volume?
Dry cement, sand and aggregate contain voids that fill as water is added and the mix is compacted, so you must batch about 54 percent more loose material than the finished wet volume.
What concrete grade should I use?
M15 for levelling and light footings, M20 for most residential slabs, beams and columns, and M25 where the structural design calls for it. Pick the grade your engineer specifies.