Block Mortar Calculator
Find how many bags of mortar you need to lay concrete blocks or bricks, and the cement, lime and sand proportions of each mortar type.
Change the values and press Calculate to work out your own figures.
Mortar for blocks
Enter the number of blocks and the mortar type.
Show the working
- 80 lb bags = blocks ÷ 12; 60 lb bags = blocks ÷ 9, rounded up
Mortar for bricks
Enter the number of bricks and the mortar type.
Show the working
- 80 lb bags = bricks ÷ 36; 60 lb bags = bricks ÷ 27, rounded up
How to use it
Enter the number of blocks and the mortar type. Enter the number of bricks and the mortar type.
Lengths can be decimals, fractions or tape entries such as 12' 6 1/2" (in feet or inches). Prices are optional.
Key facts
80 lb bags = blocks ÷ 12 (or bricks ÷ 36), rounded up 60 lb bags = blocks ÷ 9 (or bricks ÷ 27), rounded up
Mortar types
Type N (1:1:6) is the general-purpose mortar for above-grade walls; type S (2:1:9) and M (3:1:12) are stronger, for foundations, retaining walls and paving; type O (1:2:9) is for interior, non-load-bearing work.
Questions
How many bags of mortar for 100 blocks?
9 bags of 80 lb, or 12 of 60 lb.
How many bricks does a bag of mortar lay?
About 36 bricks per 80 lb bag.
Formulas
80 lb bags = blocks ÷ 12 (or bricks ÷ 36), rounded up 60 lb bags = blocks ÷ 9 (or bricks ÷ 27), rounded up
Sources
Limitations
- Material densities are typical values (the midpoint of the commonly published range); real loads vary with moisture, grading and compaction, so check with your supplier or type in their density.
- Tank results are the geometric volume; real tanks have wall thickness and fittings.