This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
181. In this country, unfortunately, there is no legal standard regulating the size of brick, and the dimensions vary not only with the maker, but also with the locality. In the New England states, the average size of common brick is about 7 3/4 in. X 3 3/4 in. X 2 1/4 in.; New York and New Jersey brick will run about 8 in. x4 in. x2 1/2 in., and the walls laid in them will run 8, 12, 16, and 20 inches in thickness for 1, 1 1/2, 2, and 2 1/2 bricks. Most of the Western common brick measure 8 1/2 in. x4 1/8 in. x 2 1/2 in., and the thickness of the walls measures about 9, 13, 18, and 22 inches for thicknesses of 1, 1 1/2, 2, and 2 1/2 bricks. On the seacoast of some of the Southern states, the brick are made with a large percentage of sand, and will average 9 in. x 4 1/2 in. X 3 in.
Most manufacturers of pressed brick use the same size mold, hence pressed brick are more uniform in size. They are generally 8f in. X 4 1/8 in. X 2 3/8 in. Pressed brick are also make 1 1/2 inches thick. There is a form used frequently, known as Roman or Pompeian brick, the size of which is 12 in. x4 in. X 1 1/4 in.
It is important that pressed brick should be made of such size that two headers and a joint will equal one stretcher, in order that a good bond may be secured; and it is also desirable that the length of a brick should equal three courses when laid.
The weight of bricks varies considerably with the material used, and also, of course, with their size. Common brick will average about 4 1/2 pounds each, while pressed brick, owing to their greater density, will weigh from 5 to 5 1/2 pounds.