The interval variety of an interval class in a scale is the number of different interval qualities available for that interval class. For example, the interval class "fifth" in the diatonic scale has interval variety 2, because there are two sizes of fifths in that scale: 6 perfect fifths and 1 diminished fifth.
The concept of interval variety can be applied to all interval classes of a scale at once. Here are some such properties:
- Highest interval variety (see also maximum variety)
- Mean interval variety
- Median interval variety
- Lowest interval variety
In addition, strict variety scales, such as single-period MOS scales and trivalent scales, have the same interval variety for all interval classes (except the unison, which always trivially has interval variety 1).