How to Calculate Brick & Mortar Quantities for Australian Projects
Whether you're building a garden retaining tier, a brick letterbox, or a structural double-skin extension, getting your material counts right matters — ordering too few leaves your project stranded mid-build, while over-ordering blows out delivery costs.
Standard Australian Brick Dimensions
A standard Australian clay utility brick measures 230mm long × 110mm wide × 76mm high. Accounting for a standard 10mm mortar joint, the nominal calculation footprint becomes 240mm × 86mm. This works out to approximately 48.5 bricks per square metre for a single-skin (half-brick) wall, and roughly 97 bricks per square metre for a double-skin (full-brick/cavity) wall — effectively double, since a cavity wall is two independent skins.
Mortar Requirements
As a real-world trade rule of thumb, standard single-skin brickwork uses approximately one 20kg bag of pre-mixed mortar for every 2 square metres of wall — around 10kg of dry mix per square metre. Double-skin walls use roughly double this, since there's twice the brickwork and joint area to fill.
Openings and Corners
Door and window openings should always be subtracted from your gross wall area before calculating bricks — skipping this step is one of the most common causes of over-ordering. Corners and returns also use extra "closer" bricks at every course to complete the bond, which this calculator estimates based on your wall height and number of corners.
Frequently Asked Questions
A standard Australian brick with a 10mm mortar joint works out to approximately 48.5 bricks per square metre for a single-skin (half-brick) wall, and roughly 97 bricks per square metre for a double-skin (full-brick/cavity) wall. This calculator applies those figures automatically once you enter your wall dimensions.
As a real-world trade rule of thumb, standard single-skin brickwork uses approximately one 20kg bag of pre-mixed mortar for every 2 square metres of wall — around 10kg of dry mix per square metre. Double-skin walls use roughly double this, since there's twice the brickwork and joint area to fill.
A double-skin (cavity) wall is really two independent single-skin walls built with a gap between them — an outer leaf and an inner leaf. Each leaf needs the same brick count as a standalone single-skin wall of that size, so the total is simply double.
Every course of brickwork at a 90° corner needs an extra closer brick to maintain the bond pattern. This calculator estimates the number of courses in your wall (height ÷ 86mm course height) and adds one extra brick per course, per corner, as a reasonable working estimate — always confirm exact detailing with your bricklayer for complex bond patterns.
For anything larger than a single brick opening, yes — it will affect your count. For genuinely tiny openings like a single weep hole, the difference is negligible and not worth tracking separately.
5% suits a straightforward rectangular wall with standard cuts. 10% is safer for complex layouts, curved sections, feature bond patterns, or if you're using recycled/irregular bricks where breakage is more common.