How the number of bricks is calculated
The brick count is the number of bricks that cover the wall's face, times the number of bricks deep the wall is. Each brick occupies its own size plus one mortar joint in every direction, so a 190 × 90 × 90 mm modular brick with 10 mm joints covers 200 × 100 mm of face, and a half-brick wall needs 50 per m². The calculator then adds a wastage allowance.
The formula
- Wall volume = Length × Height × Thickness (all converted to metres, shown for reference)
- Brick + mortar volume = (L + joint) × (W + joint) × (H + joint)
- Bricks required = Length × Height × (Thickness + joint) ÷ Brick + mortar volume, rounded up
- Total = Bricks required × (1 + wastage %), rounded up
One joint is added to the thickness because a wall n bricks deep has only n − 1 joints running through it (a 230 mm wall is two 110 mm bricks and one 10 mm joint). With it added, (Thickness + joint) ÷ (W + joint) is the number of leaves, so a half-brick wall reduces to face area ÷ ((L + joint) × (H + joint)).
Wall length and height default to metres and thickness to millimetres. The mortar joint defaults to 10 mm (editable from 0 to 25 mm) and wastage to 5% (0 to 50%).
Worked example
A wall 3 m long, 3 m high and 230 mm thick, built in standard 230 × 110 × 75 mm bricks with 10 mm joints:
- Wall volume: 3 × 3 × 0.23 = 2.070 m³.
- Brick with mortar: 0.24 × 0.12 × 0.085 = 0.002448 m³.
- Bricks: 3 × 3 × (0.23 + 0.01) ÷ 0.002448 = 882.4, rounded up to 883.
- With 5% wastage: 883 × 1.05 = 927.15, rounded up to 928 (45 extra).
That's two leaves of 441.2 bricks each, the count you'd get from the wall face alone (9 m² ÷ (0.24 × 0.085 m)). A one-brick wall in modular bricks is 190 mm thick (two 90 mm bricks and a joint) and needs 900 bricks, or 945 with wastage.
Brick sizes and counts per square metre
These are the calculator's counts for a 10 m × 10 m wall with 10 mm joints and no wastage, divided by 100:
| Brick | Size (mm) | Face with 10 mm joint (mm) | Per m², half-brick wall | Per m², one-brick wall |
|---|---|---|---|---|
| Modular | 190 × 90 × 90 | 200 × 100 | 50.0 (90 mm) | 100.0 (190 mm) |
| Standard/Classic (built in) | 230 × 110 × 75 | 240 × 85 | 49.0 (110 mm) | 98.0 (230 mm) |
| IS 1077 non-modular (use Custom) | 230 × 110 × 70 | 240 × 80 | 52.1 (110 mm) | 104.2 (230 mm) |
The modular size and the 230 × 110 × 70 mm non-modular size both come from clause 6.1 of IS 1077:1992, the Indian standard for common burnt clay bricks. Bricks sold locally often differ by a few millimetres, so measure a few from your supplier and use Custom if they don't match a preset. In the 3 m × 3 m example, switching from 75 mm to 70 mm high bricks raises the count from 883 to 938.
Getting the wall thickness right
Enter the wall's real, finished thickness. The calculator adds the one extra joint itself, so the count matches the bricks on the wall when the thickness is whole leaves plus the joints between them:
- Modular bricks: 90 mm for a half-brick wall or 190 mm for a one-brick wall.
- Standard 230 × 110 mm bricks: 110 mm or 230 mm.
A 3 m × 3 m half-brick wall in standard bricks gives 442 at 110 mm, the same as counting bricks on the wall face. A thickness that isn't whole leaves, such as 230 mm with modular bricks, gives a proportional count (1,080 for the 3 m × 3 m wall), so match the thickness to how the bricks will actually be laid.
Steps for a whole building
- Measure each wall's length and height. Treat walls of different thickness as separate runs.
- Subtract doors and windows: reduce the length, or calculate the wall in solid sections.
- Enter the thickness as described above and pick the brick size.
- Set wastage. 5% is the default; use more if bricks will be cut a lot or handled several times.
- Add up the totals across walls.
Brick footings below ground are easier with the brick foundation calculator. The room calculator gives wall areas for a whole room, the plaster calculator estimates rendering for the finished wall, and the block calculator does the same job for concrete blocks.
This is a quantity estimate for ordering. Load-bearing walls, wall thickness and openings in structural masonry should be specified by a qualified engineer or architect under your local building code.
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