Brick Calculator
Works out the bricks for a wall from its size, the brick you are using and the joint. Gives the mortar as well, since the two are always ordered together.
Includes the waste allowance — this is the figure to order.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
units per m² = 1,000,000 ÷ ((face length + joint) × (face height + joint)) units = area × units per m² × (1 + waste)
Each unit effectively occupies its own face plus one joint along two edges, because the joint is shared with its neighbour. Working from the real face size and adding the joint is the only reliable way — nominal sizes already include the joint, so adding one again counts it twice.
What to watch out for
Three things decide whether the order is right:
- 60 bricks per square metre is the UK figure for a half-brick wall with 10 mm joints. US modular works out around 6.9 per square foot. Both come straight from the face size plus the joint.
- A cavity wall is two walls. Each leaf needs its own bricks, so a cavity or one-brick wall doubles the count. This is the single most common under-order.
- Buy the whole job at once. Bricks vary between batches, and a patch of slightly different colour is permanent and obvious.
The mortar figure here adds 25% to the bare joint volume. That covers frogs — the indent in the top of many bricks, which fills with mortar — along with perforations and what ends up on the board.
Frequently Asked Questions
How many bricks per square metre?
About 60 for a UK standard brick with 10 mm joints on a half-brick wall. A one-brick or cavity wall needs 120, because it is two leaves.
How many bricks per square foot?
About 6.9 for US modular brick with a ⅜ in joint. A 100 square foot wall therefore takes around 690 bricks before waste.
How much mortar do I need per 1,000 bricks?
Around 0.37 m³ for a half-brick wall with 10 mm joints once frogs and waste are counted — roughly 6 bags of 25 kg cement and 0.6 tonnes of sand at a 1:4 mix.
How much waste should I allow for bricks?
5% on a plain straight wall, 10% where there are openings, returns or angled cuts. Reclaimed brick wants more again, since more of it breaks.