Brick Calculator
Estimate how many bricks a wall needs from its dimensions, the brick size, and the mortar joint, with a wastage allowance and bricks-per-square-metre figure.
Cómo usar esta calculadora
- 1Enter the wall's length and height, and the total area of any openings.
- 2Set the brick size and mortar joint (the defaults are a standard UK brick).
- 3Choose a single- or double-skin wall thickness.
- 4Read the number of bricks to order, including a wastage allowance.
Cómo funciona
Brick quantity
wall area = length × height − openings brick face area = (brick length + joint) × (brick height + joint) bricks per m² = (1 ÷ face area) × number of skins total = area × bricks per m² × (1 + wastage)
Estimating bricks starts from the wall's face area, less any openings for doors and windows. Each brick occupies not just its own face but a share of the mortar joint around it, so the effective face area adds the joint thickness to both the length and the height — a 215 × 65 mm brick with a 10 mm joint behaves as if it were 225 × 75 mm. Dividing one square metre by that effective face area gives the number of bricks per square metre for a single skin, which is close to 60 for a standard brick. A one-brick-thick (double skin) wall needs twice as many. Multiplying by the wall area and adding a wastage margin for cuts and breakages gives the number to order.
Ejemplo resuelto
A 10 m by 2.4 m wall has a face area of 24 m². With standard 215 × 65 mm bricks and a 10 mm joint, a double-skin wall needs about 118 bricks per square metre, or roughly 2,845 bricks — plus a 10% wastage allowance, giving about 3,130 to order.
Brick Calculator: la guía completa
Why the mortar joint changes the count
A common mistake in estimating bricks is to divide the wall area by the bare brick face, ignoring the mortar. But every brick in a wall is surrounded by mortar joints, and those joints take up real space — typically 10 mm between bricks. The brick effectively occupies its own dimensions plus one joint width in each direction, so a 215 mm long brick with a 10 mm joint really claims 225 mm of horizontal run. Ignore this and you will over-order by roughly a tenth.
This is why the calculation adds the joint to both the length and height of the brick before working out how many fit in a square metre. For the standard UK brick the result is very close to the tradesperson's rule of thumb: 60 bricks per square metre for a single-skin (half-brick) wall. That figure already bakes in a standard 10 mm joint, which is why it is quoted so consistently — it is the effective-face-area calculation done once and remembered.
Single skin, double skin, and wall thickness
How many bricks a wall needs depends heavily on its thickness. A half-brick wall, one brick wide, is a single skin — think of a garden wall or an internal partition — and uses about 60 standard bricks per square metre. A one-brick wall, the thickness of a traditional external house wall, is effectively two skins bonded together and needs roughly 120 bricks per square metre, double the single-skin figure.
Modern cavity walls complicate this further: they are two separate skins with a gap between, and the outer skin is often brick while the inner is block. When estimating, be clear about which skins are brick and count only those. The thickness selector here handles the common single- and double-skin cases; for a cavity wall with a blockwork inner leaf, estimate the brick outer skin as a single skin and the blocks separately, since blocks are far larger and counted differently.
Wastage, and what the estimate leaves out
No brick job uses exactly the theoretical number. Bricks are cut to fit at corners, reveals, and the ends of courses; some arrive broken; and a few are spoiled during laying. A wastage allowance covers this, and 10% is the usual figure for straightforward walls. Intricate work — lots of openings, curves, decorative bonds, or many cut bricks — can justify 15% or more. It is always cheaper to have a few spare than to halt work and reorder, ideally from the same batch so the colour matches.
This calculator estimates bricks only. It does not size the mortar, which depends on joint thickness, brick type (frogged or perforated bricks swallow more), and the mix, though a rough guide is about one 25 kg bag of mortar per 50 to 60 bricks. Nor does it account for special bricks at corners and copings, or the foundation and damp-proof course. Treat the brick count as the main material order and price the mortar, ties, and sundries separately.
Preguntas frecuentes
How many bricks are in a square metre?
About 60 standard bricks per square metre for a single-skin (half-brick) wall, using a 215 × 65 mm brick with a 10 mm mortar joint. A one-brick-thick (double-skin) wall needs roughly 120 per square metre. These figures already include the mortar joint.
How much wastage should I allow for bricks?
Around 10% for a straightforward wall, covering cuts, breakages, and the odd spoiled brick. Complex work with many openings, curves, or decorative bonds can need 15% or more. Ordering a little extra from the same batch avoids a colour-mismatched top-up later.
Do I subtract windows and doors?
Yes — subtract the total area of openings from the wall's face area before calculating, since no bricks go there. Enter the combined area of doors and windows in the openings field. For large openings this makes a meaningful difference to the count.
Does this include mortar?
No, it estimates only the bricks. Mortar depends on the joint thickness, the brick type, and the mix, but a rough guide is one 25 kg bag per 50 to 60 bricks. The brick count already accounts for the space the mortar joints occupy in the wall.