What is the Concrete Calculator?
A concrete calculator computes the quantities of cement, sand and aggregate required for a chosen volume and grade of concrete (M5, M7.5, M10, M15, M20, M25). It uses the standard 1.54 dry-volume factor.
Formula
Material vol = Wet vol × 1.54 × material part / total parts
- M20 mix — 1 : 1.5 : 3 (cement : sand : aggregate)
- M25 mix — 1 : 1 : 2
Step-by-step example
Setup: 1 m³ M20 concrete.
- Dry vol = 1.54 m³
- Cement = 0.28 m³ (≈ 8 bags) · Sand = 0.42 m³ · Aggregate = 0.84 m³
Answer: 8 bags + 0.42 m³ sand + 0.84 m³ aggregate per m³ of M20
Frequently asked questions
Why are grades named M5, M20 etc.?
The number is the characteristic compressive strength at 28 days in N/mm² (MPa).
M20 vs M25 — when to use which?
M20 is the minimum for RCC residential work; M25 for higher loads, columns of taller buildings, and water-retaining structures.