bricks

photo of laying brick

Bricks are sized, in the first instance, by the size of the human hand and the strength of the arm. The bricklayer lifts a brick with one hand, so its width must be small enough to fit between thumb and fingers, somewhere around 4 inches.

photo of brick wall with alternating courses

The length of the brick is then twice the width plus a slight allowance, because before the 20th century solid brick walls were at least two brick widths thick, with some bricks laid endwise and others crosswise to connect the two layers.

A brick's weight is limited to what a bricklayer can repeatedly lift easily with one hand, perhaps 12 pounds, though most bricks are half to three-quarters of that weight. Within the weight limit, depth is also limited by the properties of clay; thicker bricks are more difficult to dry and fire. Historically, depth has been the brick dimension that has varied the most. Notice that unfired bricks (adobe) are generally twice as thick as fired brick.

Within these constraints, standard sizes for bricks have been set locally and nationally for several centuries, if not millennia.

American brick grades
American nonmodular brick sizes
American modular brick sizes
Nova Scotia legal brick sizes

Bricks are usually sold in “cubes” of 500 bricks. A cube weighs about a ton.

Sources

Karl Gurke.
Bricks and Brickmaking: A Handbook for Historical Archaeology.
University of Idaho Press, 1987.