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

A minor third in just intonation corresponds to a pitch ratio of 6:5 or 1:12. while in an equal tempered tuning, a minor third is equal to three semitones, a ratio of 1:23/12 (approximately 1.189), or 300 cents, 15.641 centss smaller.

The minor third is considered the most consonant interval after the unison, octave, perfect fifth, perfect fourth, major third, and minor sixth.

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