How many bricks do I need per square metre of wall?

This depends entirely on your brick size and mortar joint thickness, which is why there is no single universal number — for a common 215mm x 65mm brick with a 10mm joint, it works out to roughly 59-60 bricks per square metre for a single skin; for other brick sizes (which vary a lot by country) the figure can be anywhere from 40 to 80+ bricks per square metre. Use the calculator with your actual brick size for an accurate figure rather than relying on a rule of thumb.

Do I need to double my brick count for a cavity wall?

Yes, roughly. A cavity or double-skin wall is built from two separate leaves of brickwork with a gap between them, so you need brick for both leaves — select "double" stack in the calculator and it will apply that multiplier automatically. The two leaves are usually tied together with wall ties rather than mortar, so the brick and mortar counts for each leaf are calculated independently, then added together.

How much waste allowance should I add when ordering bricks?

Most professional estimators use 5-10% for a straightforward wall with a simple stretcher bond and few openings, rising to 10-15% for walls with a decorative bond, lots of corners, curves, or openings, or where you are working with reclaimed/irregular bricks that have a higher breakage rate.

How do I work out how much mortar I need for a brick wall?

Mortar volume is the wall volume minus the volume the bricks themselves take up — turn on this calculator's mortar module and it will work that out automatically from your wall and brick dimensions, then split the result into cement and sand quantities (and bags of cement) based on your chosen mix ratio.

Can I use this calculator for concrete blocks instead of clay bricks?

The same area-divided-by-unit-footprint method works for any masonry unit — block, brick, or paver — as long as you enter that unit's actual face length and height. For a dedicated block-focused workflow with block-specific presets, see the concrete block calculator linked below.

What's the standard mortar joint thickness for brick in the US?

US brickwork almost universally uses a 3/8in (about 9.5mm) mortar joint as the default, which is what BIA Technical Note 10 and most brick manufacturer literature assume — use this as your starting point unless your project specifications call for a different joint width.

Do I need a permit to build a brick wall in the US?

Requirements vary by state and municipality, but most US jurisdictions require a permit for freestanding walls above a certain height (commonly 3-4ft) or for any retaining wall over a similar threshold — check with your local building department, since brick veneer on an existing structure may have different rules than a new freestanding wall.

Brick Calculator — How Many Bricks Do I Need? | US

How many bricks do I need for a wall?

The number of bricks you need depends on three things: the size of the wall, the size of the brick you are laying, and how thick the mortar joint between each brick is. Get any one of those wrong and you can end up hundreds of bricks short — or paying for hundreds you never use. This calculator does the arithmetic for you: enter your wall length and height, pick or type in your brick size, set the mortar joint thickness and a waste allowance, and it works out exactly how many bricks to order, plus how much mortar you will need to lay them.

It works for any brick, block, or paver, in any country. Brick sizes are not standardised worldwide — a UK brick, a US modular brick, and an Indian standard brick are all different sizes, and even within a country there are usually two or three common formats stocked by merchants. Rather than forcing you to guess, this tool ships with the real, sourced brick dimensions used in your country, so the default answer already matches what your local builders' merchant sells.

Whether you are building a garden wall, a boundary wall, a single-skin partition, or a full cavity/double-skin exterior wall, the same core method applies: work out the wall area, work out how much wall each brick-plus-joint actually covers, divide, and add a sensible waste margin for cuts, breakages, and mistakes. The sections below walk through exactly how that maths works, with a worked example, so you can sanity-check the number the calculator gives you or do it by hand if you just need a rough estimate on site.

This guide also covers the optional mortar module — how much sand and cement (or a pre-mixed mortar) you need to actually bed those bricks in place — plus the most common mistakes people make when ordering brick for a wall (hint: it is almost always forgetting the joint thickness, or forgetting that a double-skin wall needs roughly twice as many bricks as a single skin of the same area).

How to use the brick calculator

Enter the wall length and wall height (the area you actually need to cover with brick — if there are large openings like garage doors you plan to omit entirely, measure around them).
Choose whether you are building a single-skin (one brick thick) wall or a double-skin/cavity wall (two skins of brick, roughly double the brick count).
Select your brick size from the country presets, or enter a custom brick length and height if you are using a non-standard or reclaimed brick.
Set the mortar joint thickness — most walls use a 10mm joint (⅜" in imperial-sized brickwork), but confirm this against the brick you are actually buying.
Add a waste allowance (5-15% is typical) to cover cuts, breakages, and delivery damage.
Optionally, turn on the mortar module and choose a cement:sand mix ratio to get the mortar volume, number of cement bags, and sand quantity as well as the brick count.
Enter a price per brick (and, if using the mortar module, prices for cement and sand) to get a total estimated material cost for the wall.

The brick calculation formula

The core formula is simple once you see it laid out: the number of bricks equals the wall area divided by the area that one brick, plus its mortar joint, actually occupies on the face of the wall.

bricks = wall area ÷ [(brick length + joint) x (brick height + joint)]

The reason you add the joint thickness to both the brick length and the brick height is that every brick in a course is separated from its neighbours by a layer of mortar on all sides — so the "footprint" each brick claims on the wall is always slightly bigger than the brick itself. Skip this step and your brick count will be too low, because you have effectively assumed the bricks are laid with no mortar at all.

For a double-skin (cavity) wall, you build two separate leaves of brickwork, so you simply double the result. Then you apply your waste percentage on top, rounding up to a whole number of bricks, since merchants sell bricks by the unit (or by the pack/pallet, which this calculator's "bricks needed" figure lets you convert against your supplier's pack size).

Worked example: a wall 6m long and 2m high, built in a single skin, using a standard 215mm x 65mm brick with a 10mm mortar joint and 10% waste. Wall area = 6 x 2 = 12 m². Each brick, with its joint, occupies (0.215 + 0.01) x (0.065 + 0.01) = 0.225 x 0.075 = 0.016875 m². Raw brick count = 12 ÷ 0.016875 ≈ 711.1. Add 10% waste: 711.1 x 1.1 ≈ 782.2, rounded up to 783 bricks.

If you switch on the mortar module, the calculator works out the wet mortar volume as the wall volume minus the volume the bricks themselves occupy, multiplies by a dry-to-wet shrinkage factor (mortar loses roughly a third of its volume as it is mixed and compacted, so the dry ingredients you buy need to be about 1.5x the wet volume you will actually use), and then splits that dry volume between cement and sand according to your chosen mix ratio (commonly 1:3 for structural work, 1:4 for general purpose, or 1:5 for low-stress garden walls) before converting the cement portion into whole bags.

Typical brick sizes (reference only)

Brick sizes vary enormously by country and by brick type, which is why this calculator loads your country's real, sourced standard sizes as presets rather than a single global default. The figures below are illustrative examples only — always check the reference table for your own country (shown further down this page) or the size printed on your supplier's spec sheet, since using the wrong preset will throw off your brick count noticeably.

A "standard modular" brick in many metric countries is roughly 190-230mm long and 55-90mm high (face dimensions, excluding the joint).
Imperial-legacy brick sizes (older heritage stock, and some US formats) are usually quoted as fractions of an inch and convert to slightly different metric equivalents than modern metric bricks.
Facing bricks (the visible outer skin of a cavity wall) and structural/common bricks are sometimes different sizes even within the same country — always confirm which one you are actually ordering.
Large-format lightweight blocks (aerated concrete, hollow clay blocks) use completely different dimensions from traditional solid brick and are usually priced and counted per block, not per brick — check which material your project actually calls for.

US brick sizes

The most common US brick is the "modular" brick, with a nominal size of 8in x 2-2/3in x 4in but an actual manufactured size of 7-5/8in x 2-1/4in x 3-5/8in (194mm x 57mm x 92mm) — the gap between nominal and actual is designed to true up to the nominal module once a standard 3/8in mortar joint is added, per Brick Industry Association (BIA) Technical Note 10. A taller "engineer" brick (actual 7-5/8in x 2-3/4in, 194mm x 70mm) is also widely stocked for faster coursing with fewer joints. Always confirm the actual (not nominal) dimensions with your supplier, since brick count math depends on actual face size plus the joint, not the nominal module.

Pro tips and common mistakes

Bond pattern matters more than people expect. A simple stretcher bond (every brick laid lengthways, overlapping the course below by half a brick) is the most material-efficient and is what this calculator's formula assumes. A Flemish bond or English bond, which mix stretchers and headers (bricks laid end-on) for a decorative pattern or added strength, typically uses more brick per square metre of wall and creates more cut bricks at corners and openings — budget extra waste allowance (nearer 15% than 5%) if you are using a decorative bond.

Single-skin vs double-skin is the single biggest multiplier in this whole calculation. A single-skin (half-brick) wall is common for garden walls, planters, and non-structural partitions. A cavity or double-skin wall — standard for most modern exterior house walls — uses two separate leaves of brick with an insulated gap between them, which means roughly double the bricks (and double the mortar) of a single-skin wall of the same face area. Always confirm which your project needs before ordering: getting this wrong is the most common and most expensive brick-ordering mistake.

Do not forget door and window openings. This calculator gives you the brick count for the full wall area you enter; if your wall has openings you are not bricking over, subtract their area from your wall length x height before entering it, or measure only the brick-covered sections separately and add the results together.

Mortar mix ratio affects strength, not just quantity. A richer 1:3 cement:sand mix is used for load-bearing and below-ground work where strength matters most; a leaner 1:4 is the general-purpose default for most above-ground walls; and a lean 1:5 (or lime-based mixes) is often preferred for soft or reclaimed brick and conservation work, where a mortar joint stronger than the brick itself can cause the brick to crack before the joint does.

Buy 5-10% extra bricks even if you think your measurements are perfect. Bricks break in transit, get cut wrong, and batches from the same supplier can vary slightly in colour between production runs — ordering a small buffer from the same batch avoids an awkward colour-mismatched top-up order later.

A common mistake is treating "brick size" as just length x height and forgetting the depth (width) dimension entirely — this does not affect the bricks-per-square-metre count, but it does affect wall thickness, structural design, and how much a double-skin cavity wall's overall thickness will be, which matters for foundations and door/window reveals.

At a typical US brick price of around $0.65 per modular brick, the worked example on this page — a 6m x 2m (roughly 20ft x 6.5ft) single-wythe wall needing 783 bricks including 10% waste — comes out at roughly $509 in brick cost alone, before mortar, sand, cement, and labor.

US masons say "wythe" where this calculator uses "skin" — a single-wythe wall is one brick thick, and a double-wythe (or cavity) wall uses two separate wythes with an air space or insulation between them, tied together with wall ties rather than mortar.