Fig. 1 · F# to A#

interval

F♯ major third

F♯lowerA♯upperM34 half steps

Four half steps. The interval that makes a triad major.

On the keyboard

F#A#
Fig. 2

What is true of it

F♯ up a major third is A♯: 4 half steps, and 3 letters counting both ends.

Turn it upside down — put the F♯ on top — and it becomes a minor sixth. The two numbers always add to nine, and the two sizes to twelve.

It is a imperfect consonance.

Every interval on F♯

F♯ → Gminor second · dissonanceF♯ → G♯major second · dissonanceF♯ → Aminor 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♯ → Eminor seventh · dissonanceF♯ → E♯major seventh · dissonance

C M3C♯ M3D♭ M3D M3D♯ M3E♭ M3E M3F M3all 204