A Major 9th
Hear the A Major 9th chord played for you.
Amaj9
A – C♯ – E – G♯ – B
Formula:R-M3-P5-M7-M9
Intervals:P1-M3-P5-M7-M9
Scale Degrees:1-3-5-7-9
Introduction
The A Major 9th chord is a five-note chord made up of A, C♯, E, G♯, and B. It is built from a root, major third, perfect fifth, major seventh, and major ninth.
The A Major 9th piano chord (Amaj9) consists of the notes A, C#, E, G#, B. It is a major 7th chord with an added major 9th, giving it a lush, sophisticated character often used in jazz, R&B, and neo-soul progressions. Formula: R-M3-P5-M7-M9 | Scale degrees: 1-3-5-7-9.
Notes
Key Signature
The key of A Major 9th has 3 sharps.
F♯C♯G♯
Order of sharps
Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.
F♯C♯G♯D♯A♯E♯B♯
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of A Major
These are the diatonic triads built on each degree of the A major scale:
C
D
E
F
G
A
B
C
D
E
F
G
A
B
I — A Major (major)
Theory: Intervals
Formula: R-M3-P5-M7-M9
Intervals: P1-M3-P5-M7-M9
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.
Related Tools
Chord FinderLook up any chord — see the notes, hear it, and play along.Chord DrillTimed drills to build speed and recognition across all chord types.Practice RoomPlug in a MIDI keyboard and get real-time feedback on every chord and scale.Circle of FifthsVisualize key relationships, relative minors, and key signatures.MIDI MonitorLive MIDI message stream with note names, velocity, and a scrolling staff.