Fig. 1 · F# to E

interval

F♯ minor seventh

F♯lowerEupperm710 half steps

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

On the keyboard

EF#
Fig. 2

What is true of it

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

Turn it upside down — put the F♯ 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 F♯

F♯ → Gminor second · dissonanceF♯ → G♯major second · dissonanceF♯ → Aminor third · imperfect consonanceF♯ → A♯major third · imperfect consonanceF♯ → Bperfect fourth · perfect consonanceF♯ → B♯augmented fourth · dissonanceF♯ → Cdiminished fifth · dissonanceF♯ → C♯perfect fifth · perfect consonanceF♯ → Dminor sixth · imperfect consonanceF♯ → D♯major sixth · imperfect consonanceF♯ → E♯major seventh · dissonance

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