Mortar Calculator
Estimate the bags of mortar and cubic feet needed to lay a given number of bricks or blocks, including the sand.
How it works
bags = units ÷ units-per-bag × (1 + waste%), rounded up · brick ≈ 30/bag, block ≈ 12/bag
Mortar is estimated from how many units one bag of mix will bed. As a widely used rule of thumb, an 80 lb bag of mortar mix lays roughly 30 standard bricks or about 12 concrete blocks, since a block has far more bedding face and a wider joint. Divide your unit count by that yield, add waste for the mortar that drops off the trowel and stiffens in the pan, and round up to whole bags; a bag of pre-blended mix takes on the order of a cubic foot of sand when you mix from separate cement and sand instead.
Worked example
Laying 1,000 bricks at 30 per bag needs 1,000 ÷ 30 = 33.3 bags; add 10% waste → 37 bags of 80 lb mortar mix, and roughly 37 cu ft of sand if mixing from cement and sand.
Frequently asked questions
How many bricks does one bag of mortar lay?
A common estimate is about 30 standard bricks or 12 concrete blocks per 80 lb bag of mortar mix. The real number depends on joint thickness, brick size and how much falls off the trowel, so treat it as a planning figure.
What mortar type do I need?
Type N is the general-purpose choice for above-grade walls, Type S is stronger for below-grade and structural work, and Type M is the strongest for foundations and retaining walls. Match the type to the load and exposure, not just cost.
Should I buy pre-mixed or mix my own?
Pre-blended mortar mix is convenient and consistent for small to mid jobs — just add water. On large jobs, mixing your own cement, lime and sand can be cheaper, which is why the sand estimate matters.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.