interval
G♭ major sixth
G♭lowerE♭upperM69 half steps
Nine half steps. The minor third turned upside down.
On the keyboard
What is true of it
G♭ up a major sixth is E♭: 9 half steps, and 6 letters counting both ends.
Turn it upside down — put the G♭ on top — and it becomes a minor third. The two numbers always add to nine, and the two sizes to twelve.
It is a imperfect consonance.
Every interval on G♭
G♭ → A♭♭minor second · dissonanceG♭ → A♭major second · dissonanceG♭ → B♭♭minor third · imperfect consonanceG♭ → B♭major third · imperfect consonanceG♭ → C♭perfect fourth · perfect consonanceG♭ → Caugmented fourth · dissonanceG♭ → D♭♭diminished fifth · dissonanceG♭ → D♭perfect fifth · perfect consonanceG♭ → E♭♭minor sixth · imperfect consonanceG♭ → F♭minor seventh · dissonanceG♭ → Fmajor seventh · dissonance