How Many Bricks Do I Need?

The name includes the joint

A "modular" brick is called 8 inches long. Measure one and it's 7.625.

That isn't sloppiness. 7.625 + ⅜ = 8.0 exactly. The brick is manufactured so that brick-plus-mortar tiles neatly onto an 8-inch grid, which is what lets courses and openings line up across a whole building.

Same trap as nominal lumber — a 2×4 is neither 2 nor 4 — and it catches people the same way. Measure a brick rather than trusting the box.

The arithmetic

Each brick occupies its own face plus one joint in each direction:

bricks per sq ft = 144 ÷ ((length + joint) × (height + joint))

For a standard modular brick at a ⅜″ joint: 144 ÷ (8 × 2.625) = 6.86 per square foot.

The Brick Industry Association's estimating tables round that to 6.75. Plenty of calculators just use 7. The spread is trivial on a garden wall and material on a house — which is why this computes it from the brick you're actually laying rather than picking one.

The joint moves the count by about a seventh

This surprises people, because the joint feels like a detail:

Joint	Bricks per sq ft	vs ⅜″
¼″	7.31	+6.6%
⅜″ (standard)	6.86	—
½″	6.44	−6.1%

On the default 20 × 6 ft wall that's 966 bricks against 851 — 115 bricks decided by how the wall gets laid, not by what you ordered.

The calculator shows both alternatives beside your figure for exactly that reason.

Openings, and why the deduction is worth making

Enter doors and windows to deduct as square feet and they come straight off the net area. Worth doing properly on a house wall, where a couple of windows is easily a tenth of the order — and worth ignoring on a garden wall that has none.

One caution: deduct the opening, not the opening plus a margin. Brickwork around an opening produces cuts, and those cuts are what the waste allowance is partly for. Deducting generously and then adding waste on top double-counts the same thing in opposite directions, and the two rarely cancel neatly.

Courses rarely land on a whole number

The tool returns courses high — wall height divided by one course, where a course is the brick plus one joint.

On the default 6 ft wall at a ⅜″ joint that's 27.4 courses. Not 27, not 28.

That fraction has to go somewhere, and the options are all decisions rather than accidents: adjust the joint slightly across the wall, change the wall height, or finish with a coping or soldier course that absorbs the difference. Bricklayers plan this before the first course; it is a bad thing to discover three quarters of the way up.

Wythes double everything

A wythe is one brick's thickness of wall. Single-wythe is one brick thick; double-wythe is two, tied together.

Doubling the wythes doubles the bricks per square foot of wall face — about 13.7 on the default figures.

Which you need is a structural question, not an aesthetic one: it depends on the wall's height, what it supports and what it has to resist. That's your local code, not a calculator.

Order it all in one batch

The usual reason to over-order is breakage and cuts. That's real — 5–10% is normal.

But the better reason is colour.

Brick shade varies between production runs. A patch laid later from a different batch stays visible for the life of the wall, and matching a brick two years on is close to impossible.

Order the whole job at once, record the lot number, and keep the spares. That's why the lot number is a field on the printable.

What this counts, and what it doesn't

It counts bricks. A brick wall is a structure, and these are all separate:

• Mortar — depends on joint width, brick absorption, and how much you drop. It's the cheap part and the part that decides whether the wall lasts, so it's a poor place to economise.
• Foundations — brickwork needs them, and they're a code matter
• Wall ties, damp-proof course, movement joints
• Lintels over every opening
• Height limits on free-standing walls

Print the take-off sheet — first line is measure a real brick, and there's a field for the batch number, which is the one thing you'll wish you'd written down.

Sources: ProBuilderCalc — standard brick sizes and mortar math · CalcShed — bricks per square foot