What the Brick Quantity Calculator does
This calculator counts the bricks or blocks a wall needs from its length, height and thickness, the brick size and the mortar joint, less any doors and windows, and adds a wastage allowance. It also gives the wet volume of mortar the joints take up, which you can turn into cement and sand with the Cement and Sand Ratio Calculator.
It works from the size of one brick plus its joint, so it handles UK, Indian, US and block sizes - or any custom size - with the same arithmetic.
How to use it
- Enter the wall length and height in metres, and the total area of any openings.
- Choose the thickness: a half-brick wall is one leaf of bricks laid lengthways; a one-brick wall is two leaves (for example English or Flemish bond, or a 9-inch wall in India).
- Choose a standard brick size or enter your own in millimetres, and the mortar joint thickness (10 mm is standard in the UK and India; about 3/8 in in the US).
- Set the wastage - 5% is common for bricks, more for fragile or second-hand bricks and complicated walls - and optionally a price per brick.
Reading the results
Bricks per m² comes from the face of one brick with its joint. A UK 215 x 65 mm brick with 10 mm joints occupies 225 x 75 mm, so a half-brick wall takes 59.3 per m² - the "60 per square metre" rule of thumb.
Bricks to buy is the exact count plus wastage, rounded up. Bricks are usually sold in packs, so round up again to whole packs.
Mortar (wet) is the wall volume minus the volume of the bricks: bed joints, perpends and, in thicker walls, the collar joint between leaves.
Worked example: a UK one-brick garden wall
A garden wall is 10 m long and 1.2 m high, built one brick thick (two leaves) from 215 x 102.5 x 65 mm bricks with 10 mm joints. Its face area is 12 m².
Each brick with its joint covers 0.225 x 0.075 = 0.016875 m², so one leaf needs 1 / 0.016875 = 59.26 per m². Two leaves over 12 m² need 12 x 59.26 x 2 = 1,422.2, so 1,423 bricks are laid; with 5% wastage, buy 1,494.
The wall is 2 x 102.5 + 10 = 215 mm thick, so it occupies 12 x 0.215 = 2.58 m³. The bricks themselves fill 1,422.2 x 0.215 x 0.1025 x 0.065 = 2.037 m³, leaving 0.543 m³ of wet mortar.
Formulas and scoring rules
- Wall area
area = length x height - openings- Bricks per m² per leaf
1 / ((brick length + joint) x (brick height + joint))- Bricks
laid = ceil(area x per-m² x leaves); to buy = ceil(area x per-m² x leaves x (1 + wastage))- Wall thickness
leaves x brick width + (leaves - 1) x joint- Mortar (wet)
area x thickness - bricks x (length x width x height of one brick)
Limitations: what the result does not prove
- Frogs, perforations and cavities in bricks are ignored; frogged bricks laid frog-up take more mortar than the figure shown.
- Cavity walls are two separate half-brick leaves with a gap; calculate each leaf (or one leaf plus a block leaf) separately rather than choosing two leaves here.
- Piers, corners, returns, arches and cut bricks at openings add to the count; increase wastage for complicated walls.
- Structural questions - foundation size, wall height limits, wall ties, movement joints - are for a structural engineer and your local building regulations.
Privacy: where your data goes
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Standards and sources
- Brick Development Association - Brick sizes and specification
- Brick Industry Association - Technical Notes (including TN 10, estimating brick masonry)
Frequently asked questions
How many bricks are in a square metre?
About 60 for a UK half-brick wall (215 x 65 mm bricks with 10 mm joints give 59.3), and 120 for a one-brick wall. Indian modular 190 x 90 mm bricks with 10 mm joints give 50 per leaf per m², so 100 for a 9-inch (two-leaf) wall.
How much wastage should I allow for bricks?
5% is a common allowance for new bricks on straightforward walls. Allow 10% or more for reclaimed or fragile bricks, walls with many openings or corners, and decorative bonds that need a lot of cut bricks.
How much mortar do I need for bricklaying?
It depends on brick size and joint thickness, typically 20-25% of the wall volume for standard bricks with 10 mm joints. The calculator gives the wet mortar volume from the wall and brick sizes; the Cement and Sand Ratio Calculator turns it into cement bags and sand.
What is the difference between a half-brick and a one-brick wall?
A half-brick wall is a single leaf of bricks laid lengthways, about 100 mm thick. A one-brick wall is two leaves bonded together, about 215 mm thick in the UK or 190-230 mm elsewhere, and needs twice as many bricks per square metre of wall face.
Can I use this for concrete blocks?
Yes. Choose the concrete block preset (440 x 215 mm face with 10 mm joints gives 10 blocks per m²) or enter your block's dimensions. The same arithmetic applies to any rectangular masonry unit.
Should I subtract door and window openings from a brick wall?
Yes - enter their total area as openings. Keep the wastage allowance, because the bricks around openings often need cutting and lintels change the coursing.
Last reviewed by the A2Z.Tools team against the sources listed above.
