Amaj9 — A, C♯, E, G♯, B — is a major 9th chord: major triad + major 7th + major 9th — a lush, expansive Imaj9 sonority that defines the sound of modal-era jazz piano.
Intervals
The A major 9 chord stacks two thirds on the root. Each interval and its size in semitones:
- A→C#major 3rd4 semitones
- C#→Eminor 3rd3 semitones
- E→G#major 3rd4 semitones
- G#→Bminor 3rd3 semitones
On the keyboard
Each note of the A major 9 chord highlighted on a piano. Pitch class is what matters — any octave works.
On the guitar
One voicing of the A major 9 chord on a six-string guitar fretboard.
- 1A
- 3C#
- 5E
- 7G#
- 9B
Common mistakes
The defining note is the 9th (B). It sits more than an octave above the root, which is why the chord needs a wide voicing — in tight piano voicings the 9th usually appears in the top register while the root and lower triad tones cluster below.
In context
Functions as the Imaj9 chord in its parent major key; appears at every cadential resolution in jazz.
Drill it
The A major 9 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.
Open the Chord Trainer →Or try today's Etudle puzzleRelated
Frequently asked
- What notes are in a Amaj9 chord?
- Amaj9 contains five notes: A, C♯, E, G♯, B.
- How is Amaj9 different from Amaj7?
- Amaj9 adds the 9th (B) on top of the underlying 7th chord. The 9th extends the chord into the next octave and adds harmonic colour.
- When is Amaj9 used in music?
- Functions as the Imaj9 chord in its parent major key; appears at every cadential resolution in jazz.