B9 chord on piano
The B9 chord, or B dominant 9th, stacks 5 notes on B: B, D♯, F♯, A and C♯. Musicians write its formula 1 3 5 ♭7 9.
Notes and intervals of B9
Each note of B9 has a job. Counted from the root, you get root (B), major 3rd (D♯), perfect 5th (F♯), minor 7th (A) and major 9th (C♯). Change one of these intervals and you get a different chord, which is why the formula 1 3 5 ♭7 9 is worth memorising rather than the shape alone.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | B |
| 3 | major 3rd | D♯ |
| 5 | perfect 5th | F♯ |
| ♭7 | minor 7th | A |
| 9 | major 9th | C♯ |
How to play B9 on piano
Put your right-hand thumb on B, then add the other notes: B, D♯, F♯, A and C♯. Teachers usually suggest the fingering 1-2-3-4-5 (left hand: 5-4-3-2-1). Press the keys together, release, and repeat until the chord sounds even.
Inversions of B9
An inversion keeps the same notes but puts another one in the bass. B9 has 3 inversions besides root position: 1st inversion (D♯ F♯ A C♯ B), 2nd inversion (F♯ A C♯ B D♯) and 3rd inversion (A C♯ B D♯ F♯). Inversions let you move between chords with tiny hand movements, which is how pianists make progressions sound smooth.
Which keys use B9?
B9 is not built from the notes of a single major key, so it usually appears as a colour chord: a borrowed chord, a passing chord or a suspension that resolves to the next chord.
Scales to play over B9
These scales share every note of B9: B Mixolydian mode. B Mixolydian mode is the safest choice; the others add more colour.
About dominant 9th chords
A dominant seventh with a 9th on top: 1 3 5 ♭7 9. It keeps the tension of the 7 chord but sounds fuller, smoother and funkier, as the major ninth softens the tritone between 3 and ♭7. It belongs to the extended chords, built by stacking thirds beyond the seventh. For example C9: C E G B♭ D.
Use it wherever a V7 works: V9 to I, the dominant in ii7 V9 Imaj7, and every chord of a blues (I9 IV9 V9). Funk can sit on one 9 chord for a whole groove, and soul, gospel and jazz use it as a richer dominant. In minor keys, V7♭9 is more common than V9, because the scale has a ♭6.
Five notes are a lot: drop the fifth first, and the root too when a bass player has it. A classic split: root and ♭7 in the left hand, 3, 5 and 9 in the right. Rootless voicings such as 3 5 ♭7 9 or ♭7 9 3 5 are the standard jazz piano sound for dominant chords.
9 is not add9: a 9 chord has the ♭7, an add9 does not. 9 is not maj9 either: maj9 has the major seventh and a calm, non-dominant sound. And the 9 is a major ninth; ♭9 and ♯9 (as in E7♯9, the 'Hendrix chord') are altered versions with their own symbols.
Frequently asked questions
What notes are in the B9 chord?
B9 (B dominant 9th) contains B, D♯, F♯, A and C♯. In intervals: root (B), major 3rd (D♯), perfect 5th (F♯), minor 7th (A) and major 9th (C♯).
How do you play B9 on piano?
Play B, D♯, F♯, A and C♯ together with the right-hand fingering 1-2-3-4-5. You can also play it in 3 inversions, shown on this page.
What scale goes with B9?
B Mixolydian mode fits B9 best. Other scales that contain all its notes: B Mixolydian mode.
What key is B9 in?
B9 does not belong to a single major key. It is used as a colour chord that borrows notes from outside the key.
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