Fig. 1 · Gb to Bb

interval

G♭ major third

G♭lowerB♭upperM34 half steps

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

On the keyboard

GbBb
Fig. 2

What is true of it

G♭ up a major third is B♭: 4 half steps, and 3 letters counting both ends.

Turn it upside down — put the G♭ 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 G♭

G♭ → A♭♭minor second · dissonanceG♭ → A♭major second · dissonanceG♭ → B♭♭minor third · imperfect consonanceG♭ → C♭perfect fourth · perfect consonanceG♭ → Caugmented fourth · dissonanceG♭ → D♭♭diminished fifth · dissonanceG♭ → D♭perfect fifth · perfect consonanceG♭ → E♭♭minor sixth · imperfect consonanceG♭ → E♭major sixth · imperfect consonanceG♭ → F♭minor seventh · dissonanceG♭ → Fmajor seventh · dissonance

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