Concrete Calculators & Mix-Ratio Guides

From the geometry of a pour to the materials behind it.

Calculate the pour

Rectangle, square, circle, triangle, trapezoid or a measured custom volume.

Follow a worked example

See how 1 m³ of concrete becomes cement, sand and aggregate estimates using 1:1.5:3.

Nominal estimating ratios

Grade reference	Cement : sand : aggregate (loose dry volume)
M5	1 : 5 : 10
M7.5	1 : 4 : 8
M10	1 : 3 : 6
M15	1 : 2 : 4
M20	1 : 1.5 : 3
M25	Design mix required — no universal ratio
M30	Design mix required — no universal ratio

M5–M20 ratios are conventional loose-volume estimating references, not guaranteed strength specifications. M25 and M30 require a project-specific design mix; no universal fixed ratio applies. Use the methodology to understand model limits.