Brick Masonry is one of the oldest known man-made building materials, dating back to around 8000 B.C. Modern clay face brick comes in numerous standard sizes, most in nominal 4" widths, with nominal lengths of 8" or 12", and heights ranging from 2" to 5-1/3". Actual dimensions are normally 3/8" less than the nominal size, which allows for the typical mortar joint thickness. The most common size, "modular brick," measures 3-5/8" wide by 2-1/4" high by 7-5/8" long. This modular dimension works so that three bricks match the height and two bricks match the length of a standard nominal 8" by 16" concrete block or concrete masonry unit (CMU).