Brick Calculator Guide: How Many Bricks Do You Need?
Calculating the correct number of bricks is an important part of planning any construction project. Ordering too few bricks can delay the work, while ordering too many can increase costs and create unnecessary waste.
This guide explains how to calculate brick quantity for a wall using a simple step-by-step method.
Why Brick Quantity Calculation Matters
An accurate brick estimate helps you:
- Prepare a realistic construction budget
- Order the correct amount of material
- Reduce material waste
- Avoid delays caused by shortages
- Compare quotations from contractors and suppliers
- Plan transportation and storage requirements
Even a small calculation error can result in hundreds of extra or missing bricks on a larger project.
Information You Need Before Calculating Bricks
Before starting the calculation, collect the following details:
- Wall length
- Wall height
- Wall thickness
- Brick length
- Brick width
- Brick height
- Mortar joint thickness
- Number and size of doors and windows
- Expected wastage percentage
Make sure all measurements use the same unit, such as metres, feet, centimetres, or inches.
Basic Brick Calculation Formula
The general formula is:
Number of bricks = Net wall volume ÷ Volume of one brick with mortar
The net wall volume is the total wall volume after subtracting openings such as doors and windows.
Step 1: Calculate the Wall Area
Use the following formula:
Wall area = Wall length × Wall height
Example
Suppose a wall is:
- 5 metres long
- 3 metres high
The wall area will be:
5 × 3 = 15 square metres
Step 2: Subtract Doors and Windows
Openings should not be included in the brick calculation.
Suppose the wall contains one door measuring:
- 0.9 metres wide
- 2.1 metres high
Door area:
0.9 × 2.1 = 1.89 square metres
Net wall area:
15 − 1.89 = 13.11 square metres
If the wall contains several doors or windows, calculate the area of each opening and subtract the combined area from the total wall area.
Step 3: Determine the Wall Thickness
Brick quantity also depends on wall thickness.
Common wall thicknesses include:
- Half-brick wall
- One-brick wall
- One-and-a-half-brick wall
- Cavity wall
A thicker wall requires more bricks than a thinner wall covering the same area.
For volume-based calculations, use:
Wall volume = Net wall area × Wall thickness
Suppose the wall thickness is 0.23 metres.
Wall volume:
13.11 × 0.23 = 3.0153 cubic metres
Step 4: Calculate Brick Size Including Mortar
A brick occupies slightly more space after mortar is added around it.
Suppose the actual brick size is:
- Length: 230 mm
- Width: 110 mm
- Height: 75 mm
Assume a mortar joint of 10 mm.
The nominal brick size becomes approximately:
- Length: 240 mm
- Width: 120 mm
- Height: 85 mm
Convert these measurements to metres:
- 240 mm = 0.24 m
- 120 mm = 0.12 m
- 85 mm = 0.085 m
Nominal brick volume:
0.24 × 0.12 × 0.085 = 0.002448 cubic metres
Step 5: Calculate the Number of Bricks
Use the formula:
Number of bricks = Wall volume ÷ Nominal brick volume
Using the example:
3.0153 ÷ 0.002448 = 1,231.74
Round the result up:
Approximately 1,232 bricks
Step 6: Add Wastage
Bricks can break during transportation, cutting, handling, or installation. It is therefore sensible to include an allowance for wastage.
A typical wastage allowance is between 5% and 10%, depending on the project.
For 5% wastage:
1,232 × 5% = 61.6
Total bricks required:
1,232 + 62 = 1,294 bricks
You should therefore order approximately:
1,300 bricks
Rounding up to a practical ordering quantity gives you a small safety margin.
Complete Brick Calculation Example
Consider a wall with the following measurements:
- Wall length: 5 m
- Wall height: 3 m
- Wall thickness: 0.23 m
- Door size: 0.9 m × 2.1 m
- Nominal brick size with mortar: 0.24 m × 0.12 m × 0.085 m
- Wastage allowance: 5%
Calculation
Total wall area:
5 × 3 = 15 m²
Door area:
0.9 × 2.1 = 1.89 m²
Net wall area:
15 − 1.89 = 13.11 m²
Wall volume:
13.11 × 0.23 = 3.0153 m³
Brick volume with mortar:
0.24 × 0.12 × 0.085 = 0.002448 m³
Number of bricks:
3.0153 ÷ 0.002448 = 1,232 bricks
Including 5% wastage:
1,232 × 1.05 = 1,294 bricks
Estimated order quantity:
Approximately 1,300 bricks
Quick Brick Calculation Using Wall Area
For simple estimates, brick quantities are sometimes calculated per square metre or square foot. However, the exact number varies depending on:
- Brick dimensions
- Mortar thickness
- Wall thickness
- Brick arrangement
- Local construction practices
For this reason, area-based estimates should only be used for preliminary budgeting. A volume-based calculation is more reliable when the brick size and wall thickness are known.
Brick Quantity Formula for Multiple Walls
If you are calculating bricks for a room or complete building, calculate each wall separately.
Use:
Total brick quantity = Bricks for wall 1 + Bricks for wall 2 + Bricks for wall 3 + Bricks for wall 4
Then subtract all doors, windows, ventilation openings, and other gaps.
Alternatively, calculate the combined wall area first:
Combined wall area = Total length of all walls × Wall height
After that, subtract the total opening area and continue with the normal calculation.
How Mortar Thickness Affects Brick Quantity
Thicker mortar joints increase the space occupied by each brick unit. This means fewer bricks are required for the same wall volume.
Thinner mortar joints reduce the overall unit size, which means more bricks may be needed.
Always include the expected mortar joint when calculating the nominal brick dimensions.
How Wall Thickness Affects Brick Quantity
Wall thickness has a major impact on brick requirements.
For example, a one-brick-thick wall may require roughly twice as many bricks as a half-brick wall of the same length and height.
Never calculate bricks using wall area alone unless the wall thickness has already been included in the bricks-per-area rate.
Common Brick Calculation Mistakes
Ignoring Doors and Windows
Failing to subtract openings can significantly overestimate the required quantity.
Mixing Units
Do not multiply metres by millimetres or feet by inches without converting them first.
Using Actual Brick Size Without Mortar
The mortar joint changes the effective space occupied by each brick.
Forgetting Wall Thickness
Two walls can have the same area but require very different brick quantities because of their thickness.
Not Adding Wastage
Breakage, cutting, and handling losses are normal on construction sites.
Rounding Down
Always round the final quantity upward because bricks cannot be ordered in fractions.
Recommended Wastage Allowance
The wastage percentage depends on the type of project.
- Simple straight walls: around 5%
- Walls with several corners or openings: around 7%
- Decorative brickwork: around 10%
- Projects involving extensive cutting: 10% or more
The contractor or supplier may recommend a different allowance depending on the brick type and site conditions.
Tips for a More Accurate Brick Estimate
- Measure every wall separately
- Confirm the actual brick dimensions with the supplier
- Include the expected mortar joint
- Subtract all major openings
- Confirm the wall thickness
- Add a sensible wastage allowance
- Round the final quantity upward
- Check whether bricks are sold individually, by pallet, or by bundle
Frequently Asked Questions
How many bricks are needed for one square metre of wall?
The number depends on the brick size, mortar thickness, and wall thickness. There is no single figure that applies to every brick and wall type.
Should mortar be included in brick calculations?
Yes. Mortar affects the effective dimensions of each brick unit and therefore changes the total number of bricks required.
How much wastage should be added?
A wastage allowance of 5% is commonly used for simple walls. More complicated work may require 7% to 10%.
Should windows and doors be deducted?
Yes. Their total area should be subtracted before calculating the wall volume.
Can the same formula be used for concrete blocks?
Yes. The same general method can be used, but the block dimensions must replace the brick dimensions.
Is a brick calculator accurate?
A brick calculator can provide a reliable estimate when the measurements, brick size, mortar joint, wall thickness, and wastage percentage are entered correctly.
Final Thoughts
Brick quantity calculation becomes straightforward when the project is divided into clear steps:
- Calculate the total wall area.
- Subtract doors and windows.
- Multiply by wall thickness.
- Calculate the nominal brick volume, including mortar.
- Divide the wall volume by the brick volume.
- Add a wastage allowance.
- Round the result upward.
For a faster estimate, use the brick calculator on Calculate My Build. Enter your wall dimensions, brick size, mortar thickness, openings, and wastage percentage to estimate the number of bricks required for your project.