interval
G major seventh
GlowerF♯upperM711 half steps
Eleven half steps: a half step short of the octave, which is why it leans on it.
On the keyboard
What is true of it
G up a major seventh is F♯: 11 half steps, and 7 letters counting both ends.
Turn it upside down — put the G on top — and it becomes a minor second. The two numbers always add to nine, and the two sizes to twelve.
It is a dissonance.
Every interval on G
G → A♭minor second · dissonanceG → Amajor second · dissonanceG → B♭minor third · imperfect consonanceG → Bmajor third · imperfect consonanceG → Cperfect fourth · perfect consonanceG → C♯augmented fourth · dissonanceG → D♭diminished fifth · dissonanceG → Dperfect fifth · perfect consonanceG → E♭minor sixth · imperfect consonanceG → Emajor sixth · imperfect consonanceG → Fminor seventh · dissonance