Brick Mortar Bags Calculator
Estimate how many bags of mortar mix a brick job needs from the brick count and bricks-per-bag yield, with a waste allowance.
How it works
bags = ceil( bricks ÷ bricks-per-bag × (1 + waste%) )
Mortar use is driven by how many bricks one bag can lay, which depends on brick size and joint thickness. A standard 80 lb bag of premixed mortar lays roughly 40 modular bricks with a 3/8 inch joint; larger units or thicker joints lower that number. Divide the total bricks by that yield and add a waste allowance, since some mortar boards over and some is lost to drops and tooling.
Worked example
A 500-brick job at 40 bricks per bag is 12.5 bags. Adding 10% waste gives 13.75, rounded up to 14 bags of mortar. If you field-mix instead, budget about one cubic foot of masonry sand per bag of Portland-lime.
Frequently asked questions
How many bricks does one bag of mortar lay?
About 40 modular bricks per 80 lb bag of premixed mortar with a standard 3/8 inch joint. Utility and oversized bricks lay fewer per bag; thin brick veneer lays many more, so adjust the bricks-per-bag figure to your unit.
Premixed mortar or Portland-lime and sand?
Premixed bags are simplest for small jobs — just add water. Larger jobs are cheaper field-mixed with Portland, lime and masonry sand at a Type-N or Type-S ratio, which is why this calculator also estimates the sand.
Why add a waste factor?
Mortar drops off the trowel, dries on the board, and gets over-buttered on the first courses while you find a rhythm. Ten percent is typical; bump it up for a first-time mason or cold, fast-setting conditions.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.