How much mortar does a brick wall need?

A rough rule is about 7 cubic feet of mortar per 100 square feet of single-wythe brick wall with standard 3/8 inch joints, or roughly one 80 lb bag of pre-mixed mortar for every 30 to 35 bricks. Block walls use less mortar per square foot than brick.

What is the difference between Type S, N, and M mortar?

They differ in cement-to-lime-to-sand ratio and strength. Type N is general above-grade work, Type S is stronger for below-grade and structural masonry, and Type M is the strongest for foundations and retaining walls. Higher strength uses more cement per unit of sand.

How many bags of cement and sand do I need?

After finding the total mortar volume, the tool splits it by the selected type's cement-to-sand ratio. It then divides cement volume by the yield of a 94 lb Portland bag and sand volume by a typical bag or cubic-foot figure to give bag counts.

Why add a 10 percent waste factor?

Mortar is lost to droppings, board waste, tooling, and partial batches that stiffen before use. A 10 percent allowance is standard so you do not run short mid-course, which would force a cold joint or a second mixing session.

Should I buy pre-mixed or mix my own?

Pre-mixed bagged mortar is simplest and most consistent for small jobs. Mixing Portland cement, lime, and sand on site is cheaper at volume and lets you tune the type, but it requires accurate proportioning and is only worth it on larger work.

Mortar Mix & Volume Calculator

Mortar quantity is driven by how much joint volume a wall has, which depends on the unit size, the joint thickness, and the wall area. This calculator estimates that volume, adds a waste allowance, and converts it both into bags of pre-mixed mortar and into separate cement and sand quantities at the ratio for your chosen mortar type.

How it works

The tool starts from an empirical mortar-per-area figure that already accounts for the joint geometry of brick versus block, then scales by area and waste:

mortar volume (cu ft) = area_sqft × mortar_per_100sqft / 100 × (1 + waste)
premix bags           = ceil(volume / yield_per_bag)

For a site mix, the volume is split by the type’s cement-to-sand parts. Type N is roughly 1 part cement to 3 parts sand, Type S about 1 to 2.5, and Type M about 1 to 2.25:

cement volume = volume × (1 / (1 + sandParts))   then ÷ Portland-bag yield
sand volume   = volume × (sandParts / (1 + sandParts))

Example and tips

A 160 square foot brick wall at standard joints uses about 7 cubic feet of mortar per 100 square feet, so roughly 11.2 cubic feet, or about 12.3 cubic feet with 10 percent waste — around 12 to 14 eighty-pound pre-mixed bags depending on bag yield. Mix only what you can place in about 90 minutes; mortar that has started to set must be discarded, not re-tempered with extra water.