Major second

The musical interval of a major second is the relationship between the first note (the root or tonic) and the second note in a major scale (and also a minor scale). It is the inversion of the minor seventh.

It can be produced by starting on a high note and playing the second below or by starting on a low note and playing the second above.

A major second in just intonation corresponds to a pitch ratio of 9:8 or 1:1.125 while in an equal tempered tuning, a major second is equal to two semitones, a ratio of 1:2^2/12 (approximately 1.122), or 200 cents, 3.910 centss smaller.

The Mmjor second is considered the most dissonant interval outside of the minor second and major seventh.