How to use this calculator
- Enter or choose units.
- Enter or choose wet mortar volume.
- Enter or choose cement parts.
- Enter or choose sand parts.
- Enter or choose dry-volume factor.
- The sand updates as you type. Use Copy result or Share to keep it.
Method
Dry = Wet × (1 + Waste) × Dry factor; Sand = Dry × s ÷ (c + s); Cement = Dry × c ÷ (c + s) × Cement density; Sand mass = Sand × Sand density
- c : s
- cement-to-sand ratio by volume
- Dry factor
- extra dry material to fill voids
Worked example
- Dry volume = 1 × 1.33 = 1.33 m³.
- Sand = 1.33 × 6/7 = 1.14 m³; × 1600 kg/m³ = 1.824 t.
- Cement = 1.33 × 1/7 = 0.19 m³ × 1440 = 273.6 kg = 5.47 bags → 6 bags.
One cubic metre of 1:6 mortar needs about 1.14 m³ (1.8 t) of sand and 6 bags of cement.
What the result means
Order sand by weight or by the bulk bag, and allow for damp sand bulking up in volume. Leaner mixes such as 1:6 use more sand and less cement than 1:4.
Assumptions and limits
- Dry, loose sand is batched by volume.
- Lime or plasticiser, if used, is not included.
- Damp sand can bulk by 20–30% in volume, so a gauge box of damp sand holds less sand than it seems.
Questions
Why is the dry factor lower than for concrete?
Mortar has no coarse aggregate, so there are fewer large voids; 1.27–1.35 is typical, compared with about 1.54 for concrete.
Which ratio should I use?
It depends on the masonry unit and exposure. 1:6 is common for general brickwork and 1:4 for exposed or load-bearing work; follow your specification or local code.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.