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