Mortar
Bagged mortar from declared yield
- where
- bags
- required wet mortar (litres)
- waste (%)
- declared yield per bag (litres)
Explain this equation
This converts a required volume of wet mortar into the number of bags of a pre-mixed product, using the yield the manufacturer declares per bag.
V is the wet mortar you need, in litres. w is the waste percentage. Y is the declared yield: the litres of mixed mortar one bag makes. B is the number of whole bags. The calculator also shows the total mixed volume those bags provide.
V × (1 + w/100) is the volume including waste. Dividing by the yield per bag gives the number of bags, and the ⌈ ⌉ brackets round up, because you cannot buy part of a bag.
200 litres with 5% waste is 210 litres. At 13 litres per bag that is 16.2 bags, so 17 bags, which make 221 litres.
Watch out: use the mixed yield, not the bag weight or the dry volume. They are different numbers.
Convert required wet mortar volume into whole bags using the product yield.
Enter your values to see the result.
Good to know
Use the manufacturer’s mixed yield, not bag mass or loose dry volume. Water addition must follow the product instructions.
Sources
- MPA mortar / product-specific yield
Estimates are not design approval or British Standards compliance checks. Structural arch, retaining-wall, wind, foundation, lintel and masonry-capacity design are not performed. Use the project engineer’s specification.