A brick estimate is easiest to trust when you can see how it was built. Start with the wall area, deduct the openings, apply a brick rate that matches the actual brick and wall construction, then add any extra allowance after the base quantity. Only then convert the result into the pack quantities your chosen supplier sells.
1. Measure each wall before counting bricks
For a rectangular wall, multiply its length by its height. A wall 6 m long and 2 m high has a gross face area of 12 m².
If the job has several walls, calculate each wall separately and add the areas. That makes the estimate easier to audit than using one large combined dimension, particularly when the wall heights differ.
Keep the dimensions in the same unit before multiplying. For a metric estimate, metres are the simplest starting point.
2. Deduct doors, windows and other significant openings
Calculate the area of each opening in the same way — width × height — then subtract the combined opening area from the gross wall area. This gives the net brickwork area.
For example, if the 12 m² wall above contains one 1.0 m × 2.1 m opening, the opening is 2.1 m² and the net wall area becomes 9.9 m².
Do this before adding an extra allowance. Otherwise you can end up applying an allowance to brickwork that is not actually there. For awkward openings, piers or stepped walls, split the shape into simple rectangles rather than forcing the whole elevation into one rough average.
If you want the arithmetic done for you, the Brick Calculator lets you enter the wall and opening areas directly.
3. Use a brick rate that matches the actual brickwork
The Brick Development Association’s UK technical guidance uses the most widely used clay-brick work size of 215 × 102.5 × 65 mm and a nominal 10 mm mortar joint when explaining standard brickwork dimensions. Those figures are useful starting assumptions, but they are not a reason to ignore the product you are actually buying.
With a 215 mm × 65 mm brick face and a nominal 10 mm bed/perpend joint, the coordinating face is approximately 225 mm × 75 mm. The geometric rate is therefore about 59.3 bricks per square metre before practical rounding. That is why the familiar UK estimating rule is commonly stated as roughly 60 bricks per m² for one face of standard metric brickwork.
| Wall quantity basis | Common estimating starting point | What to verify |
|---|---|---|
| Half-brick / one-face brickwork | About 60 standard metric bricks per m² | Actual brick length/height and nominal joint |
| One-brick thickness / two-face quantity | About 120 standard metric bricks per m² | Construction, bond and actual brick format |
| Non-standard or long-format brick | Do not use 60/120 blindly | Manufacturer dimensions and project setting-out |
Brick dimensions do vary. Wienerberger, for example, publishes both the common 215 × 102.5 × 65 mm format and non-standard longer or thinner formats. If the brick size or nominal joint changes, the number of bricks per square metre changes too.
For the dimensions and rate maths in more detail, use the UK Brick Size & Bricks per Square Metre reference. The calculator also lets you replace the default dimensions with the dimensions for your chosen brick.
4. Calculate the base brick quantity
Once you have the net wall area and the appropriate brick rate, multiply them together.
Using the 9.9 m² example and a chosen rate of 60 bricks per m²:
That is the geometric/base quantity before any allowance for cuts, breakage, selection or site variation.
Keep that base figure visible. If you go straight to a padded final total, it becomes difficult to tell whether a later change came from the measured wall, the brick rate or the allowance.
5. Add an extra allowance deliberately — not automatically
There is no single extra percentage that is right for every brick job. The amount you choose can depend on the layout, number of cuts, breakage risk, colour/appearance selection, special details and how easily matching replacements could be obtained later.
The important estimating principle is to keep the allowance separate from the geometry. If, for example, you choose a 5% allowance for a 594-brick base quantity, the calculation is:
Round the final unit quantity up to 624 whole bricks before considering supplier packs.
That 5% is an example of the arithmetic, not a recommendation for every project. Use the percentage that is justified by the actual job, drawings, brick choice and supplier advice. The Waste Allowance Guide explains why base quantity and extra allowance should stay separate.
6. Turn the calculated quantity into a real order
A mathematical requirement such as 624 bricks does not necessarily mean a merchant will deliver exactly 624. Brick pack quantities vary by manufacturer, product and plant. Check the current pack quantity for the exact brick you intend to buy, then work out how many full packs or split packs your supplier can actually provide.
Do not assume that one product’s pack size applies to another. Current manufacturer product pages show pack quantities varying between brick products even where the work size is the same.
Only use this formula when the supplier requires full-pack ordering. If split packs are available, check the supplier’s actual terms instead.
For facing work, also ask whether colour/texture blending across packs or batches is recommended for the chosen product. That is a product/site-practice question rather than something a quantity formula can decide.
Worked example from wall measurement to buying quantity
- Gross wall: 6 m × 2 m = 12 m².
- Opening: 1.0 m × 2.1 m = 2.1 m².
- Net brickwork: 12 − 2.1 = 9.9 m².
- Chosen brick rate: 60 bricks per m² for this example.
- Base quantity: 9.9 × 60 = 594 bricks.
- Example chosen allowance: 5% = 29.7 bricks.
- Whole-unit planning quantity: 624 bricks after rounding up.
- Commercial order: check the exact brick’s current pack quantity and the supplier’s full/split-pack terms.
If any one of those inputs changes, change that line rather than guessing a new final total. This is the main advantage of a transparent quantity method.
Common brick-estimating mistakes
- Using gross wall area without deducting significant openings.
- Assuming 60 bricks per m² fits every brick size, joint or wall construction.
- Confusing one-face area with a one-brick-thick/two-face quantity.
- Adding a waste percentage before deducting openings.
- Rounding every small wall separately and compounding the rounding.
- Using an old or different brick product’s pack quantity.
- Treating a quantity estimate as structural design, setting-out detail or a brick specification.
Use the right Builder’s Toolkit page for the next step
- Brick Calculator — interactive wall, opening, brick-size, joint and allowance calculation.
- UK Brick Size & Bricks per Square Metre — the dimension/rate reference rather than the ordering workflow.
- Brick Wall Materials Estimator — plan bricks and mortar together as a project workflow.
- Brick Mortar Calculator — estimate wet mortar volume once the brick quantity is known.
- Mortar Estimating Guide — understand how to approach mortar quantity without assuming one universal consumption rate.
- Masonry & Concrete Calculators — browse the wider masonry tool cluster.
Brick Development Association — Designing to Brickwork Dimensions: used for the common 215 × 102.5 × 65 mm work size, nominal 10 mm joint and coordinating-dimension context.
Brick Development Association — Brick Calculator: current BDA quantity tool distinguishing single- and double-skin brickwork.
Wienerberger UK — Brick Sizes & Dimensions Explained: used to verify the common UK format and the existence of non-standard brick dimensions that change quantity assumptions.
Scope: this guide explains quantity estimating and ordering checks. It does not determine wall thickness, structural design, bond, movement-joint requirements, mortar specification, Building Regulations compliance or suitability of a particular brick. Follow the project design and current manufacturer information where those decisions matter.