Cement Calculator

Cement Calculator for Concrete and Mortar Mixes

The Cement Calculator estimates how much cement, sand, gravel, and water you need for concrete or mortar projects. Enter wet volume, dry-to-wet ratio, mix ratio, and bag size to get material quantities and cost instantly.

From wet volume to dry volume

Wet volume is the volume inside a formwork. Dry mix volume is larger because cement fills voids in sand and gravel:

$$\text{Dry volume} = \text{Wet volume} \times \text{Dry/Wet ratio} \times \left(1 + \frac{\text{Waste \%}}{100}\right)$$

Engineers commonly use a dry-to-wet ratio between 1.52 and 1.57. This calculator defaults to 1.54.

Splitting dry volume by mix ratio

For a mix ratio of cement : sand : gravel = 1 : 2 : 4, total parts = 7. Cement volume = dry volume $\times$ (1/7), sand = dry volume $\times$ (2/7), gravel = dry volume $\times$ (4/7).

Common concrete mix ratios

A 1:5:10 mix suits low-strength mass concrete (about 5 MPa). A 1:2:4 mix is common for reinforced slabs and beams (about 15 MPa). A 1:1:2 mix gives high-strength concrete (about 25 MPa) for heavily loaded columns.

Example

A 1 m³ wet volume block with 1.54 dry ratio and 1:2:4 mix needs about 0.22 m³ cement (roughly 317 kg or 7 fifty-kg bags). Water at 0.5 water-cement ratio adds about 159 liters.

Related tools: Concrete Calculator, Concrete Volume Calculator, and Brick and Mortar Calculator.