US modular brick
193.7 × 57.1 × 92.1 mm
7 5/8 × 2 1/4 × 3 5/8 in · format 203.2 × 66.7 mm · 74 per m² · North America
About this unit
The American standard. Its length is exactly modular — 7⅝ inches plus a ⅜ inch joint is 8 — but the height is not: 2¼ plus ⅜ is 2⅝, so three courses come to 7⅞ rather than 8. Bricklayers close the eighth of an inch by running the bed joint slightly fuller than the perpend, which is why the height looks arbitrary on paper and works out on site.
The size that matters is the format
A brick is never laid on its own. Add one 9.5 mm joint and the working unit becomes 203.2 × 66.7 mm, and every dimension in the wall is a multiple of that rather than of the brick.
| Actual size | 193.7 × 57.1 × 92.1 mm |
| Mortar joint | 9.5 mm |
| Format size | 203.2 × 66.7 mm |
| Per square metre, single skin | 73.81 — order 78 with 5% waste |
| Courses per metre of height | 15.00 |
| Units per metre of length | 4.92 |
Setting out
Ten courses rise 667 mm and ten units run 2032 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 North America units
| Unit | Actual | Format | Per m² |
|---|---|---|---|
| US queen brick | 194 × 70 × 79 mm | 203.2 × 79.4 | 62.0 |
| US king brick | 244 × 70 × 76 mm | 254.0 × 79.4 | 49.6 |
| US utility brick | 295 × 92 × 92 mm | 304.8 × 101.6 | 32.3 |
| US concrete block | 397 × 194 × 194 mm | 406.4 × 203.2 | 12.1 |
Frequently asked questions
What size is a us modular brick?
193.7 × 57.1 × 92.1 mm (7 5/8 × 2 1/4 × 3 5/8 in). Add the 9.5 mm joint and the working size — the format — is 203.2 × 66.7 mm.
How many bricks per square metre?
73.8 for a single skin — 74 in practice, before allowing for breakage. That comes straight from the format: 1,000,000 mm² ÷ (203.2 × 66.7) = 73.81.
How many courses per metre of height?
15.00 courses, at 66.7 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 57.1 mm brick with a 9.5 mm bed rises 66.7 mm per course, and that 66.7 is the number the wall is actually built from.