A# dominant 9th · Piano
A#9 Chord on Piano
The A#9 chord (A# dominant 9th) is built from the notes A#, D, F, G# and C. The keyboard diagram below shows exactly which keys to press. The same chord is also written Bb9; both spellings sound identical.
Chord diagrams
Notes in this chord
- A♯
- D
- F
- G♯
- C
Degrees: 1 – 3 – 5 – ♭7 – 9
Also written: Bb9
How to play
To play A#9 on piano, press A#, D, F, G# and C together. In root position the lowest note is A#, and the finger numbers follow the keys left to right in the diagram.
Theory behind the chord
Dominant ninth chords extend the dominant seventh with a ninth on top. They keep the pull of a seventh chord but sound fuller and more coloured, which is why funk and soul rhythm parts lean on them. On A#9 this structure sits on the root A#, so the degrees 1 – 3 – 5 – ♭7 – 9 map onto A#, D, F, G# and C.
Frequently asked questions
- Which notes are in the A#9 chord?
- A#9 contains the notes A#, D, F, G# and C. Relative to the root these are the degrees 1 – 3 – 5 – ♭7 – 9.
- Are A#9 and Bb9 the same chord?
- Yes. A#9 and Bb9 are enharmonically identical — the spelling differs but the frets and keys are the same. Which name is used depends on the key of the piece.
Practise A#9 on your phone
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