Calculate the number of bricks needed for a wall using wall dimensions, brick size, mortar joints, openings and a practical waste allowance.
How many bricks do you need?
The basic calculation is to divide the wall area by the area covered by one brick, including the mortar joint. For a more reliable estimate, subtract doors and windows first, then add a small allowance for cutting, breakage and waste.
Table of Contents
Measurements You Need
Before calculating the brick quantity, collect the dimensions of the wall and the bricks you plan to use. The brick dimensions matter because different brick sizes cover different areas.
- Wall length
- Wall height
- Brick length
- Brick height
- Approximate mortar joint thickness
- Dimensions of doors and windows
Measure in metres if you are working in square metres. If your brick dimensions are in millimetres, convert them before calculating the coverage area.
Calculate the Wall Area
For a simple rectangular wall, multiply the wall length by its height.
Example
Suppose a wall is 8 metres long and 3 metres high.
8 x 3 = 24 m²
The gross wall area is therefore 24 square metres.
Subtract Doors and Windows
A wall may contain doors, windows or other openings that do not require bricks. Subtract their combined area from the gross wall area before calculating the brick quantity.
Example with a door
Using the 24 m² wall above, suppose the wall contains one door measuring 0.9 m x 2.1 m.
Door area = 0.9 x 2.1 = 1.89 m²
Net wall area = 24 - 1.89 = 22.11 m²
If the wall has several openings, calculate each one separately and add their areas before subtracting the total.
Calculate Brick Coverage
Brick coverage depends on the brick's face dimensions and the mortar joint. A simple estimate can use the brick face plus the intended mortar joint in each direction.
For example, consider a brick with a face measuring 215 mm x 65 mm and a nominal mortar joint of 10 mm.
Coverage calculation
Convert the dimensions to metres:
215 mm = 0.215 m
65 mm = 0.065 m
10 mm = 0.010 m
Coverage = (0.215 + 0.010) x (0.065 + 0.010)
Coverage = 0.225 x 0.075 = 0.016875 m²
Approximate bricks per square metre = 1 ÷ 0.016875 = 59.26 bricks.
Actual brickwork can vary because mortar joints, laying patterns, brick dimensions and workmanship are not identical on every project. Use the manufacturer's dimensions or the specification for the actual bricks whenever available.
Worked Example: Bricks for a Wall
Suppose you have a wall measuring 8 m x 3 m, with one 0.9 m x 2.1 m door. Using the example brick coverage of approximately 0.016875 m² per brick, the calculation is:
Step 1: Gross wall area
8 x 3 = 24 m²
Step 2: Door area
0.9 x 2.1 = 1.89 m²
Step 3: Net wall area
24 - 1.89 = 22.11 m²
Step 4: Basic brick quantity
22.11 ÷ 0.016875 = approximately 1,310 bricks
This is the estimated brick count before adding a waste allowance.
How to Calculate Bricks for Multiple Walls
When several walls use the same brick and construction method, calculate their net areas separately or combine their net areas before applying the brick coverage.
| Wall | Length | Height | Area |
|---|---|---|---|
| Wall 1 | 6 m | 3 m | 18 m² |
| Wall 2 | 5 m | 3 m | 15 m² |
| Wall 3 | 4 m | 2.8 m | 11.2 m² |
| Total gross area | 44.2 m² | ||
Subtract the areas of all doors and windows from the combined wall area. Then divide the remaining area by the brick coverage per brick.
Add a Waste Allowance
The calculated quantity should not always be treated as the exact number to order. Bricks can break during transport or handling, and some may need to be cut around openings, corners and other details.
A modest allowance is commonly added to the calculated quantity. The appropriate percentage depends on the brick type, site conditions, cutting requirements and supplier packaging.
Example with 5% allowance
If the calculated requirement is 1,310 bricks:
1,310 x 1.05 = 1,375.5 bricks
Since bricks are purchased as whole units, round the result up to the next practical quantity. Packaging and supplier requirements may affect the final order.
Common Brick Quantity Calculation Mistakes
- Using gross wall area: Doors and windows may need to be subtracted.
- Ignoring brick size: Different brick dimensions produce different quantities per square metre.
- Ignoring mortar joints: The joint affects the effective coverage of each brick.
- Mixing units: Keep metres, millimetres and centimetres consistent during calculations.
- Ordering the exact calculated number: Breakage, cutting and site handling can create additional requirements.
- Using a generic bricks-per-square-metre figure: The correct figure depends on the actual brick and joint specification.
Brick Quantity vs. Wall Strength
A brick quantity calculation tells you approximately how many bricks are needed to cover a specified wall area. It does not determine whether a wall is structurally adequate.
Structural design can depend on wall thickness, brick or block type, mortar specification, loads, foundations, reinforcement, lateral forces and local building requirements. Structural questions should be checked against the applicable design standards and qualified professional advice.
Frequently Asked Questions
How do I calculate the number of bricks for a wall?
Calculate the net wall area, determine the coverage area of one brick including the mortar joint, then divide the net wall area by the brick coverage area. Add an appropriate allowance for waste and breakage.
How many bricks are needed per square metre?
There is no single figure that applies to every brick. The quantity depends on brick face dimensions and mortar joint size. Calculate the effective coverage from the actual brick and joint specification.
Should doors and windows be deducted?
Yes. For a more precise estimate, subtract the area of doors, windows and other openings from the gross wall area before calculating the brick quantity.
Should I add extra bricks to my calculation?
An allowance can be useful for breakage, cutting and handling losses. The appropriate amount depends on the project and the brickwork specification rather than one universal percentage.
Does the brick quantity calculation include mortar?
The calculation can account for mortar joints when determining effective brick coverage, but it does not calculate the amount of mortar material required. Mortar quantity is a separate estimate.
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