UK imperial brick
228.0 × 68.0 × 108.0 mm
8.98 × 2.68 × 4 1/4 in · format 238.0 × 78.0 mm · 54 per m² · United Kingdom
About this unit
The pre-metric British brick, still manufactured for extensions and repairs to older housing. It is 13 mm longer and 3 mm taller than the modern one, which is enough that a metric brick in an imperial wall shows as a visible step within four courses.
The size that matters is the format
A brick is never laid on its own. Add one 10.0 mm joint and the working unit becomes 238.0 × 78.0 mm, and every dimension in the wall is a multiple of that rather than of the brick.
| Actual size | 228.0 × 68.0 × 108.0 mm |
| Mortar joint | 10.0 mm |
| Format size | 238.0 × 78.0 mm |
| Per square metre, single skin | 53.87 — order 57 with 5% waste |
| Courses per metre of height | 12.82 |
| Units per metre of length | 4.20 |
Setting out
Ten courses rise 780 mm and ten units run 2380 mm. Openings, sills and damp courses are placed on those multiples wherever possible, because a wall that has to be cut to reach a dimension costs labour and shows.
Other United Kingdom units
| Unit | Actual | Format | Per m² |
|---|---|---|---|
| UK standard brick | 215 × 65 × 103 mm | 225.0 × 75.0 | 59.3 |
| UK metric modular | 200 × 75 × 100 mm | 210.0 × 85.0 | 56.0 |
| UK concrete block | 440 × 215 × 100 mm | 450.0 × 225.0 | 9.9 |
Frequently asked questions
What size is a uk imperial brick?
228.0 × 68.0 × 108.0 mm (8.98 × 2.68 × 4 1/4 in). Add the 10.0 mm joint and the working size — the format — is 238.0 × 78.0 mm.
How many bricks per square metre?
53.9 for a single skin — 54 in practice, before allowing for breakage. That comes straight from the format: 1,000,000 mm² ÷ (238.0 × 78.0) = 53.87.
How many courses per metre of height?
12.82 courses, at 78.0 mm each. Setting out from a fixed course height is why a window head or a damp course lands where it does rather than where a drawing might prefer.
Why does the joint matter so much?
Because the brick on its own is never the unit of construction. Masonry is set out on the format size — one unit plus one joint — and every dimension in a wall is a multiple of it. A 68.0 mm brick with a 10.0 mm bed rises 78.0 mm per course, and that 78.0 is the number the wall is actually built from.