A♯m9 — A♯, C♯, E♯, G♯, B♯ — is a minor 9th chord: minor triad + minor 7th + major 9th — the iim9 chord of jazz ii-V-I cadences and a workhorse for modal jazz tonics.
Intervals
The A# minor 9 chord stacks two thirds on the root. Each interval and its size in semitones:
- A#→C#minor 3rd3 semitones
- C#→E#major 3rd4 semitones
- E#→G#minor 3rd3 semitones
- G#→B#major 3rd4 semitones
On the keyboard
Each note of the A# minor 9 chord highlighted on a piano. Pitch class is what matters — any octave works.
On the guitar
One voicing of the A# minor 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 iim9 in the relative major and the im9 in modal jazz contexts.
Drill it
The A# minor 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 A♯m9 chord?
- A♯m9 contains five notes: A♯, C♯, E♯, G♯, B♯.
- How is A♯m9 different from A♯m7?
- A♯m9 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 A♯m9 used in music?
- Functions as the iim9 in the relative major and the im9 in modal jazz contexts.