Fig. 1 · D# to F##

interval

D♯ major third

D♯lowerF𝄪upperM34 half steps

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

On the keyboard

F𝄪D#
Fig. 2

What is true of it

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

Turn it upside down — put the D♯ 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 D♯

D♯ → Eminor second · dissonanceD♯ → E♯major second · dissonanceD♯ → F♯minor third · imperfect consonanceD♯ → G♯perfect fourth · perfect consonanceD♯ → G𝄪augmented fourth · dissonanceD♯ → Adiminished fifth · dissonanceD♯ → A♯perfect fifth · perfect consonanceD♯ → Bminor sixth · imperfect consonanceD♯ → B♯major sixth · imperfect consonanceD♯ → C♯minor seventh · dissonanceD♯ → C𝄪major seventh · dissonance

C M3C♯ M3D♭ M3D M3E M3F M3F♯ M3G♭ M3all 204