A measurement of type, used in copyfitting, based on the alphabet length of a particular typeface. When type needs to fit in a certain allotted portion of space, it is often necessary to determine how many characters fit in a unit of linear distance. See Copyfitting, Alphabet Length, and Character Count. See also Characters Per Pica.
'CPI is also used as a measurement of the density of information that can be stored on a magnetic tape, disk, or other type of external storage medium. (See also Bits Per Inch.)