What this calculator does
Bricks or blocks needed works out masonry units for a wall, from unit size and mortar joint thickness. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaUnits = wall area ÷ [(unit length + joint) × (unit height + joint)]
The inputs explained
| Field | What to enter |
|---|---|
| Wall length (m) | A number, measured in m. Starts at 8. |
| Wall height (m) | A number, measured in m. Starts at 2. |
| Unit length (mm) | A number, measured in mm. Starts at 230. |
| Unit height (mm) | A number, measured in mm. Starts at 76. |
| Mortar joint thickness (mm) | A number, measured in mm. Starts at 10. |
| Waste allowance (%) | A number, measured in %. Starts at 5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with wall length
Every other input is held at the calculator’s starting values while wall length varies. Select any row to load that scenario into the calculator.