Key takeaways
- A cubic metre of modular brickwork holds 500 bricks, because a 190 × 90 × 90 mm brick plus a 10 mm joint occupies exactly 0.002 m³.
- Work in volume, not area, until the very end — thickness varies and area-based rules break the moment it does.
- Mortar is about 23% of wall volume for modular brick with 10 mm joints, and needs a 1.33 dry volume factor of its own.
- Deduct openings over about 0.5 m², then add 5% wastage. Doing it in the other order under-orders every time.
Brick quantities look like the simplest calculation on site, and they generate more disputes than almost anything else. The reason is that the famous "500 bricks per cubic metre" is a derived number, tied to one specific brick and one specific joint, and it gets quoted for walls built from neither.
Where 500 comes from
The Indian modular brick, per IS 1077, is 190 × 90 × 90 mm. That size is deliberate. Add a 10 mm mortar joint to each of the three dimensions and you get a tidy 200 × 100 × 100 mm — the nominal or modular size, which is the space one brick actually occupies in a finished wall.
Bricks per m³ = 1 ÷ (0.200 × 0.100 × 0.100) = 1 ÷ 0.002 = 500
Nominal brick volume includes its share of mortar. Actual brick volume is 0.19 × 0.09 × 0.09 = 0.001539 m³.
So 500 is exact, not a rule of thumb — for that brick, with 10 mm joints. Change either and the number moves:
| Brick | Actual size (mm) | Nominal with 10 mm joint | Bricks per m³ |
|---|---|---|---|
| Indian modular (IS 1077) | 190 × 90 × 90 | 200 × 100 × 100 | 500 |
| Indian traditional | 230 × 110 × 70 | 240 × 120 × 80 | 434 |
| UK / EU standard | 215 × 102.5 × 65 | 225 × 112.5 × 75 | 527 |
| US modular | 194 × 92 × 57 | 203 × 102 × 68 | 710 |
Measure the brick that is actually on your site before trusting any of these.
That is why the first instruction in any brick calculation is: go and measure ten bricks from the delivered stack and take the average. Nominal sizes and delivered sizes drift apart, especially with locally fired brick.
Per square metre, or per cubic metre?
Both are used, and mixing them is where mistakes creep in. Volume is the robust way — it survives any wall thickness. Area is quicker but only valid for the thickness it was derived for.
For modular brick, a 100 mm half-brick wall works out at 50 bricks per m² and a 200 mm single-brick wall at 100 bricks per m². UK practice quotes about 60 bricks per m² for a half-brick wall, which is the same arithmetic on a 215 × 65 mm face.
Use area figures for a quick check. Use volume for the order.
Do not forget the mortar
Those 500 bricks are 500 nominal volumes. The bricks themselves are smaller — 0.001539 m³ each — so the rest of the cubic metre is mortar:
- Brick volume in 1 m³ of wall. 500 × 0.001539 = 0.7695 m³
- Wet mortar volume. 1 − 0.7695 = 0.2305 m³, or about 23%
- Dry volume of mortar materials. 0.2305 × 1.33 = 0.3066 m³
- Cement, at 1:6. Total parts 7 → 0.3066 ÷ 7 = 0.0438 m³ → × 1440 kg/m³ = 63 kg, about 1.26 bags per m³ of wall
- Sand, at 1:6. 0.3066 × (6 ÷ 7) = 0.263 m³
The 1.33 in step 3 plays the same role as the 1.54 in concrete mix calculations — it converts compacted wet mortar back into the loose dry material you have to buy. Mortar's factor is lower because it contains no coarse aggregate.
Mix ratios follow wall thickness: 1:6 is standard for 200 mm and thicker walls, 1:4 for 100 mm partition walls, which carry more stress per unit of mortar area.
Worked example: a wall with openings
A 200 mm single-brick wall, 10.0 m long and 3.0 m high, with one door 1.0 × 2.1 m and two windows each 1.5 × 1.2 m. Modular bricks, 10 mm joints, 1:6 mortar.
- Gross area. 10.0 × 3.0 = 30.0 m²
- Deduct openings. Door 1.0 × 2.1 = 2.1 m². Windows 2 × (1.5 × 1.2) = 3.6 m². Total deduction 5.7 m²
- Net area. 30.0 − 5.7 = 24.3 m²
- Wall volume. 24.3 × 0.20 = 4.86 m³
- Bricks before wastage. 4.86 × 500 = 2430
- Add 5% wastage. 2430 × 1.05 = 2551 → order 2550 bricks
- Wet mortar. 4.86 × 0.2305 = 1.12 m³
- Dry mortar volume. 1.12 × 1.33 = 1.49 m³
- Cement. 1.49 ÷ 7 = 0.213 m³ × 1440 = 307 kg → 6.1 bags, order 7
- Sand. 1.49 × (6 ÷ 7) = 1.28 m³ (45.1 cft)
Note the order of operations in steps 3 to 6. Openings come off the area, then wastage goes on the brick count. Applying wastage to the gross area instead — a common shortcut — inflates the order by the wastage on bricks that were never going to be laid.
Openings and wastage, properly
- Deduct openings above roughly 0.5 m². Standard measurement practice ignores anything smaller, because the cutting waste around a small opening roughly cancels the brick saved.
- Do not forget the lintel. The lintel over each opening displaces brickwork too. On a wall with many openings it is worth deducting.
- 5% is the normal wastage. It covers handling breakage and the cut bricks at corners, jambs and closers.
- Raise it to 7–8% for reclaimed brick, brittle local brick, or walls with a lot of small openings — every opening means cut bricks.
- Order in full lots. Bricks are delivered by the thousand. Round up to the delivery unit rather than the exact figure.
Frequently asked questions
How many bricks in 1 m³?
500 modular bricks. A 190 × 90 × 90 mm brick with a 10 mm joint occupies a nominal 200 × 100 × 100 mm = 0.002 m³, and 1 ÷ 0.002 = 500 exactly. Other brick sizes give other numbers — check the table above.
How many bricks per square metre?
For modular brick: 50 per m² in a 100 mm half-brick wall, 100 per m² in a 200 mm single-brick wall. UK bricks give about 60 per m² for a half-brick wall.
How much cement and sand for brick mortar?
For 1:6 mortar in modular brickwork, roughly 1.26 bags of cement and 0.26 m³ of sand per cubic metre of wall. Use 1:4 for 100 mm partition walls.
Should I deduct small openings?
Not below about 0.5 m². The cutting waste around a small opening broadly offsets the brickwork saved, which is why standard measurement practice leaves them in.