Major sixth

The musical interval of a Major sixth is the relationship between the first note (the root or tonic) and the sixth note in a Major scale. It is the inversion of the minor third. It can be produced by starting on a high note and playing the sixth below or by starting on a low note and playing the sixth above.

A Major sixth in just intonation corresponds to a pitch ratio of 5:3 or 1.6666. while in an equal tempered tuning, a Major sixth is equal to eight semitones, a ratio of 1:2^8/12 (approximately 1.587), or 800 cents, 15.641 centss wider. The ratios of both Major and minor sixths are corresponding numbers of the fibonacci sequence, 5 and 8 for a minor third and 3 and 5 for Major (the golden ratio lies between the minor sixth and the major sixth).

In the common practice period sixths, along with their inverse, thirds, are considered the most interesting and dynamic consonances. The Major sixth is considered the most consonant interval after the unison, octave, perfect fifth, perfect fourth, and the major third.