Question 1

How much mortar do I need per square metre of brickwork?

Accepted Answer

A standard single-leaf brick wall (215×65mm bricks, 10mm joints) uses roughly 20–25 litres of wet mortar per square metre. This calculator works it out from your exact wall size, masonry unit, and mortar type.

Question 2

What's the difference between Type M, S, N, and O mortar?

Accepted Answer

Per ASTM C270, Type M (1:0.25:3) is strongest at 2,500 psi for foundations and below-grade work. Type S (1:0.5:4.5) at 1,800 psi suits structural walls. Type N (1:1:6) at 750 psi is the most common choice for above-grade residential brickwork. Type O (1:2:9) at 350 psi is for interior, non-load-bearing walls only.

Question 3

How many 80 lb bags of pre-mixed mortar do I need?

Accepted Answer

Each 80 lb (~36 kg) bag of pre-mixed mortar yields about 10.5 litres of wet mortar. Divide your total mortar volume by 10.5 to get the bag count — this calculator does that for you automatically, including your waste allowance.

Question 4

Should I use sharp sand or builder's sand for mortar?

Accepted Answer

Use builder's (soft) sand for brick and block mortar — it has rounder, finer particles that give a workable mix. Sharp sand is coarser and is meant for concrete and screeding, not mortar joints.

Mortar calculator