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Brick Calculator

How many bricks a wall needs, for typical kiln bricks or the full 9 × 4.5 × 3 inch standard size, leaving out doors and windows and adding a little for breakage.

Rules last checked 12 November 2026Every step shown1 source

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ft
ft
sq ft

Area to leave out. A standard door is about 3 × 7 ft = 21 sq ft.

Measure a few of your bricks and pick the closer size.

in

3/8 inch (about 10 mm) is usual.

%

Bricks

1,847

Masonry volume
134.3 cft
Bricks per cubic foot
13.1

A 20 × 10 ft wall, 9 inches thick, needs about 1,847 typical kiln bricks (about 8¾ × 4¼ × 2¾ inches), including 5% for breakage.

How it's worked out

  1. Wall area20 × 10 − 21 sq ft179 sq ft
  2. Volume179 sq ft × 9 in ÷ 12134.25 cft
  3. Bricks per cft with mortar1,728 ÷ (9.125 × 4.625 × 3.125)13.1
  4. Bricks with breakage134.25 × 13.1 × 1.051,847

How bricks are counted

Bricks per cft = 1,728 ÷ ((length + j) × (width + j) × (height + j)), with the brick's size and the mortar joint j in inches

Pakistan Standard P.S. 208 sets a brick of 9 × 4.5 × 3 inches, but most kiln bricks are smaller: a PCSIR survey of Lahore kilns found most about 15% short of the standard volume. The calculator uses about 8¾ × 4¼ × 2¾ inches unless you pick the full size.

The wall volume in cubic feet is the area, minus openings, times the thickness. Multiply by bricks per cft and add breakage.

Worked example

A 20 × 10 ft wall, 9 inches thick, with one 3 × 7 ft door, is 179 sq ft and 134.25 cft. With typical kiln bricks and 3/8-inch joints that's 13.1 bricks per cft, about 1,759 bricks, or 1,847 with 5% for breakage. Full-size 9 × 4.5 × 3 inch bricks give 11.2 per cft, about 1,504 bricks, or 1,580 with breakage.

Questions people ask

How many bricks are in one cubic foot?

About 13 for the bricks most kilns sell (about 8¾ × 4¼ × 2¾ in) with a 3/8-inch joint, or about 13.5 to 14 once you add 5% for breakage. That's why builders quote 1,350 bricks per 100 cft. A brick made to the full standard size of 9 × 4.5 × 3 inches gives about 11.2 per cubic foot. Measure a few of your bricks and pick the closer size.

How many bricks for a 9-inch wall?

Each square foot of a 9-inch wall is 0.75 cft, so about 9.8 typical kiln bricks (8.4 of the full standard size). A 20 × 10 ft wall with no openings takes about 1,966 kiln bricks before breakage.

Does this include mortar?

The joint is counted in each brick's space, so the count is right for a mortared wall. Mortar itself (cement and sand) is a separate quantity.

Formula and rules last checked 12 November 2026Written and tested by the CalculatorDex teamReport a problem

Sources: Beg et al. (1989), Evaluation of Quality of Red Bricks Available in Lahore Region, Pak. J. Sci. Ind. Res. 32(8), PCSIR (cites Pakistan Standard P.S. 208:1962)