Brick count per square foot depends on the brick size and the joint width. Modular brick with 3/8 inch joints works out to seven per square foot of wall face, which is the figure most estimates use.
Sizes and coverage
Modular is the common US brick and gives seven per square foot. Queen size is slightly larger at about 5.75, and utility brick — much bigger — is three.
Those figures already include the mortar joint. Changing joint width from 3/8 to 1/2 inch changes the count by several percent.
Veneer is not structural
Most residential brick is a single-wythe veneer hung on a wood-framed wall, not load-bearing masonry. It needs metal ties to the framing, an air gap behind it, flashing at the base, and weep holes.
The weep holes are what let water out of the cavity. Bricking straight against sheathing with no gap and no weeps traps water in the wall.
Mortar and sand
Roughly one 70 pound bag of mortar mix per 125 bricks with standard joints. Pre-mixed bags already contain sand; pure masonry cement needs sand added at about three parts to one.
Mix only what can be laid in about 90 minutes. Mortar that has begun to set cannot be revived with water without losing strength.
Blending across pallets
Brick colour varies between pallets, sometimes noticeably, because firing conditions differ between kiln runs.
Masons pull from three or four pallets at once and mix as they lay, which distributes the variation so evenly that nobody sees it. Working one pallet dry before opening the next produces horizontal colour bands across the wall.
This is the reason to have the whole order on site before starting, rather than ordering more partway through.
Weep holes and the cavity
Brick veneer is not waterproof — water passes through brick and mortar and runs down the back face. The cavity behind it and the weep holes at the bottom are what let that water out.
Weeps go in the head joints of the first course above the flashing, typically every two to three feet. Blocked or omitted weeps trap water at the base of the wall against the framing.
Mortar droppings falling into the cavity during construction are what block them, which is why a mortar net or a clear cavity matters as much as the weeps themselves.