interval
D♭ perfect fourth
D♭lowerG♭upperP45 half steps
Five half steps. Turned upside down it becomes a perfect fifth.
On the keyboard
What is true of it
D♭ up a perfect fourth is G♭: 5 half steps, and 4 letters counting both ends.
Turn it upside down — put the D♭ 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 D♭
D♭ → E♭♭minor second · dissonanceD♭ → E♭major second · dissonanceD♭ → F♭minor third · imperfect consonanceD♭ → Fmajor third · imperfect consonanceD♭ → Gaugmented fourth · dissonanceD♭ → A♭♭diminished fifth · dissonanceD♭ → A♭perfect fifth · perfect consonanceD♭ → B♭♭minor sixth · imperfect consonanceD♭ → B♭major sixth · imperfect consonanceD♭ → C♭minor seventh · dissonanceD♭ → Cmajor seventh · dissonance