Fig. 1 · Ab to Fb

interval

A♭ minor sixth

A♭lowerF♭upperm68 half steps

Eight half steps. The major third turned upside down.

On the keyboard

F♭Ab
Fig. 2

What is true of it

A♭ up a minor sixth is F♭: 8 half steps, and 6 letters counting both ends.

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

It is a imperfect consonance.

Every interval on A♭

A♭ → B♭♭minor second · dissonanceA♭ → B♭major second · dissonanceA♭ → C♭minor third · imperfect consonanceA♭ → Cmajor third · imperfect consonanceA♭ → D♭perfect fourth · perfect consonanceA♭ → Daugmented fourth · dissonanceA♭ → E♭♭diminished fifth · dissonanceA♭ → E♭perfect fifth · perfect consonanceA♭ → Fmajor sixth · imperfect consonanceA♭ → G♭minor seventh · dissonanceA♭ → Gmajor seventh · dissonance

C m6C♯ m6D♭ m6D m6D♯ m6E♭ m6E m6F m6all 204