interval
G♭ perfect fourth
G♭lowerC♭upperP45 half steps
Five half steps. Turned upside down it becomes a perfect fifth.
On the keyboard
What is true of it
G♭ up a perfect fourth is C♭: 5 half steps, and 4 letters counting both ends.
Turn it upside down — put the G♭ on top — and it becomes a perfect fifth. The two numbers always add to nine, and the two sizes to twelve.
It is a perfect consonance.
Every interval on G♭
G♭ → A♭♭minor second · dissonanceG♭ → A♭major second · dissonanceG♭ → B♭♭minor third · imperfect consonanceG♭ → B♭major third · imperfect consonanceG♭ → Caugmented fourth · dissonanceG♭ → D♭♭diminished fifth · dissonanceG♭ → D♭perfect fifth · perfect consonanceG♭ → E♭♭minor sixth · imperfect consonanceG♭ → E♭major sixth · imperfect consonanceG♭ → F♭minor seventh · dissonanceG♭ → Fmajor seventh · dissonance