Major, minor and perfect intervals

Tell an interval's quality by counting semitones and build it on any note.

The size of an interval

The thirds from C to E and to E♭ span the same number of letters but sound different: the first has 4 semitones, the second 3. So besides its number, an interval has a quality: "major third" and "minor third".

A major third (C4–E4) and a minor third (C4–E♭4)

Count the semitones: four up to E4, three up to E♭4

Seconds, thirds, sixths and sevenths come as major and minor; the minor one is a semitone smaller.

Interval Semitones

minor second 1 major second 2 minor third 3 major third 4 minor sixth 8 major sixth 9 minor seventh 10 major seventh 11

Practice: Build seconds and thirds

Practice: Eight semitones

Practice: Major or minor third?

Perfect intervals

The unison, fourth, fifth and octave are not major or minor: they are perfect. A perfect unison has 0 semitones, a fourth 5, a fifth 7, an octave 12.

Between the fourth and the fifth, at 6 semitones, lies a special interval, the tritone: an augmented fourth or a diminished fifth. It has a topic of its own in the next course.

A perfect fourth, a perfect fifth and a perfect octave above C4

A handy check is the major scale: from the tonic up to each of its degrees, every interval is major or perfect. C–E is a major third, C–F a perfect fourth, C–B a major seventh.