Brick Calculator
Calculate the number of bricks or concrete blocks, and the mortar, needed for a wall — based on its area, openings, wall thickness and waste allowance.
Includes a 10% waste allowance.
Brick and block estimates are approximate. Check your chosen material dimensions, joint size and supplier guidance before ordering.
Mortar quantities are approximate and can vary with material size, joint thickness, wall thickness, workmanship and mix.
Check the openings
This calculator provides an approximate materials estimate only. Brick and block requirements depend on material size, bond, joint thickness, wall design, openings, cuts, site conditions and local building requirements. For structural work, retaining walls, foundations or work requiring Building Regulations or code approval, consult a qualified professional.
How to use this calculator
- Choose Metric or Imperial measurements.
- Choose Bricks or Concrete blocks as the material.
- Enter the wall length and height.
- Choose the wall thickness and the brick or block type.
- Add the size of any doors, windows or other openings.
- Select a waste allowance.
- The calculator estimates the bricks or blocks, and the mortar, required.
How to calculate how many bricks you need
The calculator finds the wall area, subtracts doors and windows, then divides the remaining area by the working face area of one brick, including mortar joints. It applies the selected wall thickness and waste allowance before rounding the final quantity up to a whole brick.
- net wall area = gross wall area − total opening area
- working brick face = (brick length + joint) × (brick height + joint)
- bricks required = net wall area ÷ working brick face × wall leaf multiplier
- bricks to buy = bricks required × (1 + waste ÷ 100), rounded up
Example: a 5 m × 1.8 m single-skin wall, standard UK brick
- 5 × 1.8 = 9 m² of wall, with no openings to subtract.
- The working face is (0.215 + 0.010) × (0.065 + 0.010) = 0.016875 m².
- 9 ÷ 0.016875 = 533 bricks before waste.
- With a 10% allowance, 533.3 × 1.10 rounds up to 587 bricks to buy.
Standard UK brick size
A standard UK brick measures 215 mm long × 102.5 mm deep × 65 mm high. With a 10 mm mortar joint, the working face is approximately 225 mm × 75 mm.
For a single-skin wall, this works out at around 60 bricks per square metre. A double-skin wall uses approximately twice as many bricks. The calculator uses the visible face of the brick, so the brick depth does not change the count.
Standard UK concrete block size
Standard UK concrete blocks, sometimes called breeze blocks, are commonly 440 mm long × 215 mm high. They are available in different thicknesses, including 100 mm, 140 mm and 215 mm.
With a typical 10 mm mortar joint, the working face of a 440 mm × 215 mm block is 450 mm × 225 mm. This means one block covers approximately 0.101 m², so allow around 10 blocks per square metre of wall.
| Thickness | Typical use |
|---|---|
| 100 mm | Partitions and single-leaf walls |
| 140 mm | Wider wall construction |
| 215 mm | Thicker or load-bearing walls |
These uses are general and non-prescriptive. Block thickness, bond and wall design depend on the project and its structural requirements, so confirm the specification before ordering.
Standard US concrete block size
In the United States, concrete blocks are commonly called concrete masonry units, or CMUs. A standard CMU is usually described by its nominal size of 8 × 8 × 16 inches.
The actual block is commonly about 7 5/8 inches high × 7 5/8 inches thick × 15 5/8 inches long. The block is made 3/8 inch smaller than its nominal dimensions so that mortar joints create an 8 × 8 × 16 inch module when laid.
With 3/8-inch mortar joints, a standard 8 × 8 × 16 inch CMU covers 128 square inches, or about 0.889 square feet. Allow approximately 1.125 blocks per square foot before openings and waste.
| Nominal size | Typical actual size |
|---|---|
| 8 × 8 × 16 in | 7 5/8 × 7 5/8 × 15 5/8 in |
| 6 × 8 × 16 in | 5 5/8 × 7 5/8 × 15 5/8 in |
| 4 × 8 × 16 in | 3 5/8 × 7 5/8 × 15 5/8 in |
All three standard sizes share the same 8 × 16 inch nominal face, so they use the same 1.125 blocks per square foot. The listed thickness changes the wall thickness but not the block count per square foot of wall face for these standard 8 × 16 inch modules.
Metric and imperial brick measurements
The calculator converts every measurement into a single internal wall area before showing results in the selected measurement system.
| Metric | Imperial |
|---|---|
| Wall area in square metres (m²) | Wall area in square feet (ft²) |
| Standard UK brick: 215 × 102.5 × 65 mm | US modular brick: 7 5/8 × 3 5/8 × 2 1/4 in |
| Typical mortar joint: 10 mm | Typical mortar joint: 3/8 in |
| About 60 bricks per m² for a single skin | About 6.75–7 bricks per ft² for a single wythe |
| Mortar shown in m³ and litres | Mortar shown in cubic feet (ft³) |
How much mortar do I need?
Mortar requirements vary with brick size, joint thickness, bond pattern, wall thickness and workmanship. This calculator uses an approximate mortar allowance based on net wall area and wall thickness. Check supplier guidance and project requirements before ordering materials.
How much brick waste should I allow?
A waste allowance helps cover cuts, breakages, damaged bricks, colour selection and site losses. For straightforward work, 5% to 10% is a useful starting estimate. Consider a higher allowance for complex openings, detailed brickwork or projects with many cuts.