Work out how many bricks a wall needs, including a mortar-joint allowance and wastage margin.
Based on a standard 9×4.5×3 inch brick with 10mm mortar joints on all sides. Actual brick sizes vary slightly by manufacturer — check with your supplier for large orders.
Bricks aren't laid edge-to-edge — a roughly 10mm mortar joint surrounds each one. That joint adds up: ignoring it in a rough length×height÷brick-size calculation overstates how many bricks you actually need, since it doesn't account for the extra volume the joints occupy.
A 4.5-inch (half-brick) wall is typically used for internal partitions and boundary walls with limited load. A 9-inch (full-brick) wall is standard for external and load-bearing walls in residential construction.