Brick Calculator

The formula

Brick counts come from the face area of the wall and how many bricks of your chosen size fill one square foot of that face, mortar joints included:

Wall area      = length × height
Bricks (raw)   = area × bricks per sq ft
Bricks (final) = ceil( bricks raw × (1 + waste / 100) )
Mortar bags    = ceil( bricks final / 120 )

Bricks per square foot depend on the unit size (these include a standard 3/8“ mortar joint):

Worked example

A garden wall 20 ft long and 8 ft high in modular brick, with 10% waste:

• Area = 20 × 8 = 160 sq ft
• Raw bricks = 160 × 6.86 = 1,097.6
• With 10% waste = 1,207.4 → 1,208 bricks
• Mortar = 1,208 ÷ 120 = 10.07 → 11 bags

Switch to queen size and the same wall needs roughly 812 bricks, larger units cover more area, so they cut the count and the cost.

Common pitfalls

• Forgetting the second wythe. A single-brick (4“) wall uses the count above. A double-wythe (8“) wall is two layers, double the bricks.
• No waste factor. Cuts at corners and openings, plus breakage, eat 5–10% on a straightforward job and more on anything curved or detailed.
• Mixing brick sizes. The per-square-foot figure is size-specific; a standard-size estimate run with queen bricks will be off by ~15%.
• Ignoring openings. Doors and windows reduce the count. Subtract their area from the wall area before ordering on large jobs.

A rule of thumb: about 7 modular bricks per square foot with a 3/8“ joint. The calculator is just that rule, made exact for your wall and padded for waste.