Brick Calculator
Inputs
| Wall area | 20 m² |
|---|---|
| Brick type | US modular (≈74 / m²) |
| Waste allowance | 10 % |
Brick Calculator
Estimate how many bricks and bags of mortar you need for a wall, based on the wall area, brick type, and a waste allowance.
Inputs
Results
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Details
A wall of 20 m² built with this brick type needs about ... bricks and roughly ... bags of mortar (≈ ... bricks per m²).
Brick Quantity
The number of bricks a wall needs comes from three things: the face area of the wall, the size of the brick, and how much waste to allow for breakage and cuts. Each brick size covers a known number of bricks per square metre of wall once the standard 10 mm3/8 inch mortar joint is included, so the estimate is a straightforward area calculation.
The area × coverage method
Multiply the wall face area by the bricks-per-m² figure for your brick size, then add a waste allowance for breakage and cuts:
bricks=area×bricks per m2×(1+waste)The bricks-per-m² figure already accounts for a standard mortar joint. Because bricks are sold whole, the result is rounded up to the next brick.
For mortar, a useful rule of thumb is that one standard bag lays about 125 bricks at a normal joint. So the bag count is the brick count divided by 125, rounded up:
mortar bags=⌈125bricks⌉Worked example
A 20 m² wall built with US modular bricks (about 73.84 bricks per m²) and a 10% waste allowance:
bricksmortar bags=20×73.84×1.10=1624.5→1625 bricks (rounded up)=⌈1625÷125⌉=13 bagsSo a 20 m² single-wythe modular wall needs roughly 1,625 bricks and 13 bags of mortar.
A 215 sq ft wall built with US modular bricks (about 6.86 bricks per sq ft) and a 10% waste allowance:
bricksmortar bags=215×6.86×1.10=1622.4→1623 bricks (rounded up)=⌈1623÷125⌉=13 bagsSo a 215 sq ft single-wythe modular wall needs roughly 1,623 bricks and 13 bags of mortar.
Choosing a brick type
Brick size drives the count. US modular bricks are the smallest of the three options here, so they need the most bricks per square metre (about 74). Queen-size bricks are taller and cover the same area with fewer units (about 65 per m²). UK metric bricks are larger again, at roughly 60 per m². Picking the size that matches the bricks you will actually buy keeps the estimate accurate.
Why allow for waste
Some bricks arrive cracked, others break when cut to fit corners, returns, and openings, and a few are rejected for chips or colour. A waste allowance covers those losses and leaves spares for future repairs. Five to ten percent suits a plain straight wall; raise it toward fifteen percent for walls with many cuts, curves, or decorative bonds.
These figures assume a single-wythe wall with standard 10 mm3/8 inch joints. A double-wythe (two-brick-thick) wall needs roughly twice the bricks, and thicker joints or hollow bricks change the mortar yield, so confirm against your supplier's coverage data and buy a small surplus.
For the foundation or footing beneath the wall, see the Concrete Volume Calculator.
Frequently Asked Questions (FAQ)
How many bricks do I need?
Multiply the wall face area by the number of bricks that cover one square metre for your brick size, then add a waste allowance. A single-wythe wall of US modular bricks needs about 74 bricks per square metre once the standard 10 mm mortar joint is included. For a 20 m² wall with a 10% allowance, that is roughly 1,625 bricks. Always round up, because bricks are sold whole and you will want a few spares.
Multiply the wall face area by the number of bricks that cover one square foot for your brick size, then add a waste allowance. A single-wythe wall of US modular bricks needs about 6.9 bricks per square foot once the standard 3/8 in mortar joint is included. For a 215 sq ft wall with a 10% allowance, that is roughly 1,625 bricks. Always round up, because bricks are sold whole and you will want a few spares.
How much mortar will I need?
As a rough rule, one standard bag of bricklaying mortar lays about 125 bricks at a normal 10 mm joint, so this calculator divides the brick count by 125 and rounds up. The real figure depends on joint thickness, brick frog and perforation, and how much mortar is wasted on the board. Thicker joints or hollow bricks use noticeably more, so buy a little extra rather than running short mid-course.
As a rough rule, one standard bag of bricklaying mortar lays about 125 bricks at a normal 3/8 in joint, so this calculator divides the brick count by 125 and rounds up. The real figure depends on joint thickness, brick frog and perforation, and how much mortar is wasted on the board. Thicker joints or hollow bricks use noticeably more, so buy a little extra rather than running short mid-course.
Why add a waste allowance?
Some bricks arrive cracked, others break when cut to fit corners, returns, and openings, and a few are rejected for colour or chips. A waste allowance covers these losses and leaves spares for future repairs. Five to ten percent is usual for a plain straight wall; raise it toward fifteen percent for walls with many cuts, curves, or decorative bonds.
Disclaimer
This is an estimate based on typical bricks-per-m² figures and a standard mortar yield. Actual quantities vary with brick dimensions, joint thickness, mortar mix, wall thickness (single vs double wythe), and site waste. Confirm against your supplier’s coverage data and buy a small surplus.
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