Brick Calculator

The Bureau of Indian Standards fixes the modular brick at 190 × 90 × 90 mm under IS 1077:1992. That is the actual, physical size of the brick before any mortar. It is smaller than the older “traditional” non-modular brick (230 × 115 × 75 mm) that many yards still supply, which is why this tool asks you which wall you are building rather than guessing.

The modular size is designed to work in a tidy 100 mm grid once the mortar is added — a brick plus its joint comes to a round 200 × 100 × 100 mm. That neat unit is what makes 100 bricks land in a square metre of 9-inch wall.

A brick is never laid tight against its neighbour. IS 2212:1991 sets a 10 mm mortar joint — 10 mm on the bed below and 10 mm on the vertical (perpend) face. Adding that joint turns the 190 × 90 × 90 mm brick into a 200 × 100 × 100 mm laying unit, and it is the laying unit, not the bare brick, that decides how many fit in a wall.

9" wall: 1 m² ÷ (0.2 m × 0.1 m face) = 50 faces × 2 brick depths = 100 bricks

This is why joint thickness is not a detail to hand-wave. If a mason lays fat 15–20 mm joints to stretch the brick count, the wall uses fewer bricks than the code figure — you were billed for 100/m² but fewer went in — and the extra mortar is both weaker and more prone to cracking. A thin, consistent 10 mm joint is what the IS rate assumes, and what this calculator counts.

Bricks are only laid in the solid part of the wall, so every door and window has to come out of the area first. Multiply each opening’s width by its height, add them up, and enter the total in the openings field. The tool subtracts it before counting bricks.

• Standard door — about 0.9 × 2.1 m ≈ 1.9 m².
• Standard window — about 1.2 × 1.2 m ≈ 1.44 m².
• Ventilator — about 0.6 × 0.45 m ≈ 0.27 m².

Skipping this step is one of the most common ways a brick order is over-quoted. On a wall with a door and two windows you can easily be deducting 5 m² — that is 500 bricks on a 9-inch wall that you would otherwise pay for and never use.

Take the calculator’s default: a 10 m long, 3 m high, 9-inch wall with no openings. The gross area is 10 × 3 = 30 m². With nothing to deduct, the net area is the same 30 m². At the IS rate of 100 bricks per m²:

30 m² × 100 bricks/m² = 3000 bricks → order 3150–3300 with 5–10% wastage

So 3000 bricks are actually laid, and you would buy roughly 3150 to 3300 to cover breakage and cutting. If that same wall had a 0.9 × 2.1 m door, you would deduct 1.9 m², leaving 28.1 m² and 2810 bricks before wastage.