How To Calculate Bricks Needed

Every brick count starts from area. Measure the wall, take off the openings, and you have the surface that has to be covered. Everything after that is a conversion from square feet to individual units.

The conversion is where people go wrong, because a brick does not cover its own face size. Mortar sits between every brick, so the unit that actually tiles the wall is the brick plus half a joint on each side.

A standard US modular brick is 8 inches long and 2.25 inches high. Add a three eighth inch mortar joint and each brick claims 8.375 by 2.625 inches, which is 21.98 square inches.

Divide 144 square inches in a square foot by that 21.98 and you get 6.5501 bricks per square foot. The rule of thumb quoted on site is about seven per square foot, which is the same number rounded up for safety.

Openings come straight off the total. A door and a window in a 160 square foot wall can easily remove 21 square feet, which is more than 130 bricks, so skipping this step is the most expensive shortcut available.

Waste covers cuts, breakage and the special shapes needed at corners. Five percent suits a plain wall with few openings, ten percent suits a wall with many cuts, and anything with a decorative bond needs more.

The second way to count is by courses. A course is one horizontal row, and the number of courses is the wall height in inches divided by the brick height plus the joint, rounded up.

The two methods disagree slightly, and that is expected. The course method rounds every partial brick up to a whole one at the ends of the wall, so it always runs a little higher than the area method.

Units are the classic trap. Brick dimensions are quoted in inches while wall dimensions are in feet, so the face area has to be converted through the 144 square inches in a square foot before anything else happens.

Custom sizes are fine as long as you stay consistent. Queen size, oversize and reclaimed bricks all work in the same formula once you enter their real dimensions and the joint you intend to use.

Pavers are a different calculation. They cover a horizontal surface, usually with a wider gap and sometimes with sand instead of mortar, so a wall brick count will not transfer to a patio.

Order a little more than the number you calculate. Bricks are sold by the thousand, batches vary in colour, and running out mid wall means a second delivery that may not match.

Corners, pillars and gable ends need their own measurements. A gable is a triangle, so its area is half the base times the height, and it is usually forgotten until the scaffold goes up.

Mortar is a separate quantity. The number of bags depends on the joint thickness and the brick absorption, not on the brick count directly, so it has to be estimated on its own.

A 20 by 8 foot wall with a 21 square foot opening works out at 956 bricks. The wall is 37 courses tall and 29 bricks long per course, which is a useful cross check on the area number.