Calculators/ Masonry & Aggregate/Mortar Calculator
Mortar Calculator
Mortar bags for a given number of bricks or blocks.
Mortar comes two ways: pre-blended mix where you only add water, and masonry cement that you mix with sand on site. Pre-blended is easier and far more expensive; cement plus sand is what a professional crew uses on anything larger than a garden wall.
How this is calculated
- One 80 lb bag of pre-blended mortar mix lays about 35 modular bricks or 13 standard concrete blocks.
- Mixing your own, a 70 lb bag of masonry cement plus roughly 0.14 tons of sand does the work of about 4.5 pre-blended bags.
- Add 10% waste. Mortar that stiffens on the board past its working time has to be thrown away, and that happens more than beginners expect.
Frequently asked questions
What type of mortar should I use?
Type N is the general-purpose choice for above-grade walls. Type S is stronger and used below grade or where wind and seismic loads matter. Type M is for foundations and retaining walls.
How long does mixed mortar stay usable?
About two hours in mild weather, much less in heat or wind. It can be re-tempered with a little water once, but never twice.
Is pre-blended mortar worth the extra cost?
For anything under a few hundred units, yes. Beyond that the price difference becomes significant and mixing your own is worth the effort.