We can measure intervals in musical tones and semitones. One semitone is the closest possible distance between two different notes. Adjacent quality types differ from each other by one semitone:
diminished < ((minor < Major) || Perfect) < Augmented
Therefore diminished unison contains a paradoxical number of semitones - minus one semitone. Perfect unison has no distance between its notes at all. Augmented unison, as well as the minor second, contains one semitone. And finally, the major second contains one whole tone.
Intervals that extend beyond the octave represent repetitions of the relationships formed by the intervals within the octave. Such intervals are called a compound. Among them, only ninth has an independent meaning in harmony.