Fig. 1 · Gb to Fb

interval

G♭ minor seventh

G♭lowerF♭upperm710 half steps

Ten half steps. The interval that sits on top of a dominant seventh chord.

On the keyboard

F♭Gb
Fig. 2

What is true of it

G♭ up a minor seventh is F♭: 10 half steps, and 7 letters counting both ends.

Turn it upside down — put the G♭ on top — and it becomes a major second. The two numbers always add to nine, and the two sizes to twelve.

It is a dissonance.

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♭ → E♭major sixth · imperfect consonanceG♭ → Fmajor seventh · dissonance

C m7C♯ m7D♭ m7D m7D♯ m7E♭ m7E m7F m7all 204