Mortar Mix Calculator
Enter the mortar volume and cement-to-sand ratio (e.g. 1:4) to instantly calculate the cement bags (50 kg), sand volume and total weight for brick, plaster and stonework quoting.
Input Data
Results
At a glance:Mortar follows a volumetric parts ratio: let cement parts be c and sand parts be s, total parts = c + s. Volume with waste V = mortar volume × (1 + waste%). Total weight = V × wet density; cement weight = total weight × c/(c+s), sand weight = total weight × s/(c+s). Cement bags = cement weight ÷ bag weight (rounded up). Loose sand volume = sand weight ÷ loose sand density (1,500 kg/m³).
Formula
V = volume × (1 + waste%)
Total weight = V × wet density
Cement weight = total weight × c/(c+s)
Sand weight = total weight × s/(c+s)
Cement bags = ⌈cement weight ÷ bag weight⌉
Sand volume = sand weight ÷ 1500
$$V = V_0 (1 + w)$$$$W_t = V \,\rho$$$$W_c = W_t \frac{c}{c+s}$$$$W_s = W_t \frac{s}{c+s}$$$$B = \left\lceil \frac{W_c}{b} \right\rceil$$How to Use
- Enter the mortar volume (m³).
- Choose the cement : sand ratio (1:4 common for bricklaying).
- Confirm the mortar wet density and cement bag weight.
- Set the waste (default 10%).
- The tool outputs cement bags, cement weight, sand volume and total weight.
Case Studies
Brick wall laying
1 m³ mortar, ratio 1:4, wet density 2,000, waste 10%.
Total 2,200 kg; cement 440 kg (9 × 50 kg bags), sand about 0.59 m³.
External wall plastering
0.5 m³ mortar, ratio 1:5, wet density 2,000, waste 10%.
Total 1,100 kg; cement 183 kg (4 bags), sand about 0.37 m³.
FAQ
What does 1:4 mean?
It means 1 part cement volume to 4 parts sand volume. A larger number means more sand, lower mortar strength and lower cost.
Why use loose density 1,500 for sand?
Sand is loose when stockpiled and batched, less dense than compacted solid. 1,500 kg/m³ is a common loose density for wet sand in Hong Kong, used for purchasing reference.
How does wet density affect the result?
Wet density directly sets the total weight and thus the cement/sand split. Ordinary cement-sand mortar is about 2,000–2,200 kg/m³.
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References
Content review: Calculatorism Construction Team. Results are for reference only; please refer to the relevant authorities for the official figures.