What is the Cement Calculator?
A cement calculator tells you how many 50 kg cement bags you need for a given volume of concrete or area of plaster. It uses the standard dry-volume bulking factor of 1.54 and the chosen mix ratio.
Formula
Cement bags = (Wet volume × 1.54 × cement part / total parts × 1440 kg/m³) / 50
- 1.54 — Wet-to-dry volume bulking factor
- 1440 — Density of dry cement in kg/m³
Step-by-step example
Setup: 1 m³ of M20 concrete (1 : 1.5 : 3 mix).
- Dry vol = 1.54 m³
- Cement vol = 1.54 × 1 / 5.5 = 0.28 m³
- Cement kg = 0.28 × 1440 = 403 kg → 8.06 bags
Answer: ≈ 8 bags of cement per m³ of M20 concrete
Frequently asked questions
Why multiply by 1.54?
Concrete shrinks when wet ingredients combine. Dry volume needs to be ~54% more than wet to compensate.
Which grade for slab vs column?
M20 is the minimum recommended for RCC slabs and columns in residential builds; use M25 for higher loads.