Brickwork estimates come down to one idea: a wall is a volume, and each brick with its share of mortar takes up a known part of that volume.
Brick sizes in India
| Brick | Actual size (mm) | Size with 10 mm joint (mm) | Bricks per m³ |
|---|---|---|---|
| Modular | 190 × 90 × 90 | 200 × 100 × 100 | 500 |
| Conventional (9" × 4½" × 3") | 230 × 110 × 75 | 240 × 120 × 85 | ≈ 408 |
Modular sizes are specified in IS 1077. Conventional bricks are still widely used; measure the bricks you are actually buying, because sizes vary between kilns.
Step 1: wall volume
Deduct doors and windows. A 9-inch wall is 230 mm (0.23 m) thick; a 4½-inch wall is 115 mm.
Step 2: number of bricks
Step 3: mortar and materials
Dry mortar = wet mortar × 1.33
Cement (m³) = dry ÷ (1 + n) · Sand (m³) = dry × n ÷ (1 + n)
Here n is the sand part of a 1 : n mortar. The 1.33 factor (you will also see about 1.27) allows for the bulking of dry sand and cement. Cement converts to bags at 1,440 kg/m³ and 50 kg per bag.
WORKED EXAMPLE · 9-INCH WALL, CONVENTIONAL BRICK, 1:6 MORTAR
Wall 20 × 10 ft, no openings: 6.096 × 3.048 × 0.23 = 4.274 m³One brick with joint: 0.24 × 0.12 × 0.085 = 0.002448 m³
Bricks = 4.274 ÷ 0.002448 = 1,746; with 5% wastage and rounded up to whole bricks, 1,834
Solid brick volume = 1,746 × 0.23 × 0.11 × 0.075 = 3.313 m³
Wet mortar = 4.274 − 3.313 = 0.961 m³ → dry = 0.961 × 1.33 = 1.279 m³
Cement = 1.279 ÷ 7 = 0.183 m³ → 5.3 bags (buy 6)
Sand = 1.279 × 6 ÷ 7 = 1.096 m³ (≈ 39 cft)
Practical allowances
- Breakage and cutting: 5% is a common allowance on bricks; more for poor-quality bricks or complicated walls.
- Mortar mix: 1:6 is common for 9-inch walls and 1:4 for 4½-inch partition walls, but always follow the project specification.
- Frogs: bricks with a frog (indent) take extra mortar if laid frog up and filled.
Do it on your phone
The NANDIX brick calculator handles modular, conventional and custom bricks, deducts openings, and gives cement bags and sand in cft. Optional prices turn it into a material cost.
