Sand and Cement Calculator
Work out the sand and cement needed for a volume of 4:1 mortar.
Sand required
0.8tonnes
- Cement
- 7 × 25 kg bags
- Mix volume
- 0.5 m³
Based on a 4:1 sand to cement mix, about 320 kg of cement per cubic metre.
v1.0 · Reviewed September 2026
How this is worked out
The mix volume is area × thickness. That volume is converted to sand at 1.6 tonnes per cubic metre, and cement is taken at 320 kg per cubic metre of mixed mortar, then rounded up to whole 25 kg bags.
Worked example
- Area 10 m²
- Thickness 50 mm
10 × 0.05 = 0.5 m³; sand 0.5 × 1.6 = 0.8 tonnes; cement 0.5 × 320 = 160 kg, so 7 bags
0.8 tonnes of sand and 7 × 25 kg bags of cement
Assumptions and limits
- Sand is measured loose at 1.6 tonnes per cubic metre and cement at 320 kg per cubic metre of mixed mortar. Because sand bulks and the cement fills the voids between grains, the two figures are not a simple 4:1 by weight.
- No allowance is made for waste, droppings or partly used bags.