interval
A major third
AlowerC♯upperM34 half steps
Four half steps. The interval that makes a triad major.
On the keyboard
What is true of it
A up a major third is C♯: 4 half steps, and 3 letters counting both ends.
Turn it upside down — put the A 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 A
A → B♭minor second · dissonanceA → Bmajor second · dissonanceA → Cminor third · imperfect consonanceA → Dperfect fourth · perfect consonanceA → D♯augmented fourth · dissonanceA → E♭diminished fifth · dissonanceA → Eperfect fifth · perfect consonanceA → Fminor sixth · imperfect consonanceA → F♯major sixth · imperfect consonanceA → Gminor seventh · dissonanceA → G♯major seventh · dissonance