How many 73 mm bricks per square metre? (Scottish and imperial bricks)
A 73 mm brick on the metric 215 x 102.5 mm plan, the Scottish standard, lays about 53.5 bricks per square metre with a 10 mm joint; a 228 x 108 x 73 mm imperial brick about 50.6. Both are fewer than the 59.3 per square metre of a 65 mm metric brick, because each course is 83 mm instead of 75. A 10 m² single-skin wall is 536 Scottish or 507 imperial bricks before waste, 563 and 532 with 5%. The tables give the count for 68, 73 and 80 mm imperial bricks, the joint sizes, courses per metre and walls of 10 to 100 m².
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Bricks per square metre by height
Single skin, stretcher bond, 10 mm bed and perpend joints. The 215 x 102.5 mm plan is the metric standard (BS EN 771 work size), made 73 mm tall for Scotland; the 228 x 108 mm plan is the pre-metric 9 x 4 1/4 in brick, sold by UK makers and reclamation yards in 68, 73 and 80 mm heights (2 5/8, 2 7/8 and 3 1/8 in). Each brick takes up its own face plus one joint along and one joint up, so the count is one over (length + 10) x (height + 10). Per square foot is the same figure divided by 10.764.
| Brick | Size | Per m² | Per sq ft | Courses per m |
|---|---|---|---|---|
| Metric standard, 65 mm | 215 x 102.5 x 65 mm | 59.3 | 5.51 | 13.33 |
| Scottish 73 mm (metric plan) | 215 x 102.5 x 73 mm | 53.5 | 4.97 | 12.05 |
| Imperial 73 mm (2 7/8 in) | 228 x 108 x 73 mm | 50.6 | 4.7 | 12.05 |
| Imperial 68 mm (2 5/8 in) | 228 x 108 x 68 mm | 53.9 | 5 | 12.82 |
| Imperial 80 mm (3 1/8 in) | 228 x 108 x 80 mm | 46.7 | 4.34 | 11.11 |
The 68 mm imperial brick comes out close to the Scottish 73 mm one, at 53.9 per square metre, because the extra length cancels the lower course. The bricks per square metre guide has the 65 mm brick, blocks and the US modular brick side by side.
What the joint does to the count
Old imperial work was often laid with thinner joints than the 10 mm of today, and a thick joint is the usual way to make 73 mm bricks course with an existing wall. Every millimetre on the joint comes off the count on two sides.
| Brick | 8 mm joint | 10 mm joint | 12 mm joint |
|---|---|---|---|
| Scottish 73 mm (metric plan) | 55.4 | 53.5 | 51.8 |
| Imperial 73 mm (2 7/8 in) | 52.3 | 50.6 | 49 |
Courses and gauge
Gauge is what matters on site: a 73 mm brick with a 10 mm joint is an 83 mm course, so the rod is marked at 83 mm, not 75. The table shows how many courses reach a given height and where each format lands.
| Height | 65 metric | 73 Scottish | 73 imperial | 68 imperial | 80 imperial |
|---|---|---|---|---|---|
| 1 m | 14 (1,050 mm) | 13 (1,079 mm) | 13 (1,079 mm) | 13 (1,014 mm) | 12 (1,080 mm) |
| 2 m | 27 (2,025 mm) | 25 (2,075 mm) | 25 (2,075 mm) | 26 (2,028 mm) | 23 (2,070 mm) |
| 2.4 m | 32 (2,400 mm) | 29 (2,407 mm) | 29 (2,407 mm) | 31 (2,418 mm) | 27 (2,430 mm) |
| 3 m | 40 (3,000 mm) | 37 (3,071 mm) | 37 (3,071 mm) | 39 (3,042 mm) | 34 (3,060 mm) |
A 2.4 m storey is 32 courses of 65 mm brick and 29 of 73 mm; if the lintels and the damp course have to line up with the old work, set out from the existing courses and let the top adjust.
Bricks to order for a wall
Whole walls with 5% for cuts and breakages, no openings taken off. For a double-skin (215 mm) solid wall in Flemish or English bond, the count per square metre of wall roughly doubles: put the wall in the brick calculator as two skins, or as one skin with the block preset for the inner leaf.
| Wall | 65 mm metric | 73 mm Scottish | 73 mm imperial |
|---|---|---|---|
| 10 m² | 623 | 563 | 532 |
| 20 m² | 1,245 | 1,125 | 1,064 |
| 30 m² | 1,867 | 1,687 | 1,595 |
| 50 m² | 3,112 | 2,812 | 2,658 |
| 100 m² | 6,223 | 5,623 | 5,316 |
Imperial bricks are sold by the pallet in whatever count the maker packs, and reclaimed ones by the lot; get the pack size before rounding up. Mortar for the joints is in the mortar per 100 bricks guide.
Frequently asked questions
- How many 73 mm bricks per square metre?
- 53.5 per square metre for a 215 x 102.5 x 73 mm brick and 50.6 for a 228 x 108 x 73 mm imperial brick, both with a 10 mm joint in stretcher bond, single skin. Order 56 or 53 per square metre once 5% for cuts and breakages is in.
- Why is it 60 per square metre for a normal brick but fewer for 73 mm?
- A 65 mm brick plus its 10 mm joint is a 75 mm course, 13.33 courses per metre; a 73 mm brick makes an 83 mm course, 12.05 per metre. Same length, fewer courses, so 53.5 instead of 59.3. The imperial brick is also 13 mm longer, which takes the count down again to 50.6.
- How many imperial bricks do I need for 50 m²?
- 2,532 bricks of 228 x 108 x 73 mm before waste and 2,658 with 5%; 2,812 for the 215 mm 73 mm brick. Take doors and windows off the wall area first, and count the openings' cut bricks in the waste. The calculator does any area and opening.
- Can I mix 73 mm bricks with 65 mm ones?
- Not in the same wall: every 8 courses the 73 mm side is 64 mm higher and the bed joints stop lining up, which is exactly the problem when extending an older house. Match the height first (73 mm to 73 mm), then the length; a 215 mm 73 mm brick against 228 mm imperial work needs the perpends adjusted and looks it. Reclamation yards and makers of imperial ranges exist for this reason.
- How much mortar per square metre for 73 mm bricks?
- Geometrically about 0.016 m³ per square metre for the 215 mm brick and 0.017 m³ for the imperial one, against 0.018 m³ for a 65 mm brick: fewer joints per metre of height. Frogs, perforations and what falls off the board push the real figure up, so treat it as a minimum when ordering sand and cement.
More guides
- How many bricks per square metre (and per square foot)?
Bricks and blocks per square metre and per square foot for the common formats, how the mortar joint changes the count, and what to order for a 10 m² wall.
- How many bricks per square foot? Walls, patios and floors
Modular bricks per square foot of wall (about 7) and laid flat on a patio (4.5 to 5), bricks for 100 to 500 sq ft with 5% waste, mortar, and the UK brick per sq ft.
- How many bricks do I need for a fire pit? 30, 36 and 48 inch
Bricks per course and in total for round fire pits of 30 to 48 in inside diameter at 3 to 5 courses, in modular, UK and fire brick sizes, with 5% waste, and square pits.
- How many blocks for a retaining wall? (12x4, 16x6 and 18x8 in)
Retaining wall blocks for 10 to 50 ft walls at 1, 2 and 3 ft high in the three common sizes, plus the gravel base and the drainage stone behind the wall, and metric.
Last updated 2026-09-22. Figures are planning estimates from typical product data: check the yield, size or coverage printed on what you buy and round up.