Music Intervals — Perfect, Major, Minor & More
Explore all 17 music intervals from perfect unison through the major thirteenth — the mathematical building blocks of melody, harmony, and chord construction. Every interval includes the semitone count, just intonation ratio, ear training reference, and note pair examples. See also the chord reference and scale reference for how intervals combine into larger structures.
What Is a Musical Interval?
An interval is the distance in pitch between two notes. Intervals are the most fundamental unit of music theory — scales are defined by their interval patterns, chords are built by stacking intervals, and melodies are sequences of intervals moving up and down. If you can identify intervals by ear, you can transcribe music, improvise fluently, and tune your instrument with confidence.
Intervals are classified by two properties: size (unison, second, third, fourth, fifth, sixth, seventh, octave, and compound intervals like ninths and thirteenths) and quality (perfect, major, minor, augmented, or diminished). A perfect fifth spans 7 semitones, while a diminished fifth spans 6 — just one semitone of difference, but a dramatic change in sound. Perfect intervals (unison, fourth, fifth, octave) sound open and stable; major intervals sound bright; minor intervals sound darker and more expressive.
In just intonation, intervals are expressed as simple frequency ratios — the perfect fifth is 3:2, the major third is 5:4. These pure ratios produce the most consonant sound but limit key changes. Equal temperament slightly adjusts every interval so that all 12 keys are equally usable, trading perfect consonance for universal flexibility. Understanding this trade-off helps musicians choose the right tuning system for their instrument and repertoire.
Ear training begins with intervals. Associating each interval with a familiar melody — the perfect fourth with "Here Comes the Bride," the minor second with the Jaws theme — builds instant recognition that transforms your musicianship. Use the reference below to study every interval's semitone count, just ratio, and ear training examples.