In post-tonal theory, integer notation is the use of the integers 0 through 11 to label the chromatic pitch-classes, rather than the traditional letter names; "0" is used to label any C or B-sharp, "1" to label any C-sharp or D-flat, "2" to label any D, and so on up to "11" for any B or C-flat.

These numeric labels greatly simplify the task of calculating intervals, and hence of calculating interval-classes and relating various pitch-class set-classes to each other.