A Major 9th
Introduction
Notes
A Major 9th Inversions
| Position | Notes |
|---|---|
| Root Position | A4 – C#5 – E5 – G#5 – B5 |
| 1st Inversion | C#5 – E5 – G#5 – A5 – B5 |
| 2nd Inversion | E5 – G#5 – A5 – B5 – C#6 |
Key Signature
The key of A Major 9th has 3 sharps: F♯, C♯, G♯.
Theory: Intervals
The A Major 9th is built by stacking intervals from the root note. The formula R-M3-P5-M7-M9 describes the scale degrees used. The intervals P1-M3-P5-M7-M9 show the distance between each note in the chord.
A Major 9th — Frequently Asked Questions
What notes are in the A Major 9th chord?
The A Major 9th chord (Amaj9) contains five notes: A (root), C# (major third), E (perfect fifth), G# (major seventh), and B (major ninth). It is Amaj7 with an added ninth.
How does Amaj9 differ from A9?
Amaj9 has a major seventh (G#). A9 has a minor seventh (G). Amaj9 is dreamy; A9 is dominant and bluesy.
How is Amaj9 used in music?
Amaj9 is a lush tonic in A Major. It appears in folk-jazz, acoustic music, and contemporary worship where A Major is a common key.
What songs use Major 9th chords?
Major 9th chords appear in neo-soul, jazz, and lo-fi. Amaj9 is common in acoustic and worship settings.
How does Amaj9 differ from Aadd9?
Amaj9 includes the major seventh (G#). Aadd9 has no seventh.
Do I need to play all five notes?
No — drop the fifth: A–C#–G#–B is the practical voicing.
Practice Tips
- Play Amaj7 then add B — hear the lush expansion.
- Drop the fifth: A–C#–G#–B is standard.
- Amaj9 is beautiful in acoustic settings — try it as a rich tonic chord.
- Practice Bm9 → E13 → Amaj9 for the ii–V–I in A.
- Rootless: C#–E–G#–B (C#m7 shape) for jazz comping.
- Compare Amaj9 with Aadd9 — the major seventh adds warmth.