B7♭9 chord
B dominant seventh flat nine. The dominant seventh flat nine chord: a dominant seventh with the ninth lowered a semitone. It is tense and altered, and common in jazz.
Click a note to hear it
- Notes
- B D♯ F♯ A C
- Formula
- 1 3 5 ♭7 ♭9
- Intervals
- P1 M3 P5 m7 m2
- Also written
- B7♭9
Notes in B7♭9
B7♭9 is spelled B D♯ F♯ A C: five notes stacked from the root B.
| Note | Interval above B | Role | Formula |
|---|---|---|---|
| P1 | root | 1 | |
| M3 | third | 3 | |
| P5 | fifth | 5 | |
| m7 | seventh | ♭7 | |
| m2 | ninth | ♭9 |
Inversions
Putting a different chord tone in the bass gives each inversion. The chord is the same; the bass note changes how it sounds and what it can lead to.
| Position | Notes, low to high | Symbol | Hear it |
|---|---|---|---|
| Root position | B D♯ F♯ A C | B7♭9 | |
| First inversion | D♯ F♯ A C B | B7♭9/D♯ | |
| Second inversion | F♯ A C B D♯ | B7♭9/F♯ | |
| Third inversion | A C B D♯ F♯ | B7♭9/A | |
| Fourth inversion | C B D♯ F♯ A | B7♭9/C |
On the piano
The root position voicing, with every chord tone lit in its own colour. Click a key to hear it.
On the guitar
There is no standard moveable shape for B7♭9, so here are its tones on the neck. Pick the notes that suit your voicing.
What it sounds like
C7♭9 is C, E, G, B♭ and D♭: a dominant seventh with the ninth lowered by a semitone. The D♭ sits a semitone above the octave, so it grates against the root. That close clash, together with the tritone between E and B♭, makes the chord sharp and tense. The chord pulls strongly toward a tonic, and the flattened ninth intensifies the pull. It sounds altered and biting, and it is more directional than a plain dominant seventh.
How it is used
A dominant seventh with a flat nine is an altered dominant, sitting on the fifth degree and resolving to a tonic a fifth lower. Jazz writers place it on the V of ii, V, I progressions, often in place of a plain dominant seventh. The chord keeps the dominant's resolution, with the seventh falling to the third of the tonic and the root moving down a fifth. The flat nine adds a sharp colour to the approach.
How it is built
The chord is a root with a major third, a perfect fifth, a minor seventh and a minor ninth, 0, 4, 7, 10 and 13 semitones above the root. Common symbols are C7♭9, C7(♭9) and C7-9. The flat nine, D♭, is the same pitch as C♯, so the chord can be seen as a dominant with a raised root, though it is written as a ninth. Inversions place E, G, B♭ or D♭ in the bass. The fifth can be omitted in performance without changing the chord's identity.
Which keys contain B7♭9
B7♭9 is not built from any one major or minor key’s own notes. It appears through borrowing, alteration or chromatic voice leading, which is part of why it sounds coloured.
Scales that fit B7♭9
Scales that contain every note of the chord, so they can be played over it:
Other B chords
How to practise it
Play G7, then G7♭9, then C, and listen for the A♭ falling to G in the chord of C. G7♭9 is G, B, D, F and A♭. Then move the A♭ up to A, which gives G9, to hear how one semitone changes the tension. Keep the root in the bass so the chord's identity stays clear.
Further reading
- Chord Extensions Explained: Ninths, Elevenths and ThirteenthsJazz & Popular Harmony · 7 min
- Tritone Substitution: The subV7 Chord That Still ResolvesHarmony · 6 min
- Chord-Scale Theory Explained: Which Scale Fits Which ChordJazz & Popular Harmony · 7 min
Questions
What notes are in a B7♭9 chord?
B7♭9 contains B, D♯, F♯, A, C. That is the root, third, fifth, seventh, ninth of the chord.
How do you spell B dominant seventh flat nine?
Stack the intervals P1, M3, P5, m7, m2 above B: B, D♯, F♯, A, C.
What other symbols mean B7♭9?
Lead sheets also write it B7♭9. They are the same chord.
What is the difference between C7 and C7♭9?
C7 is C, E, G and B♭. C7♭9 adds D♭, the flattened ninth, which sits a semitone above the octave. The added note makes the chord tense and more directional, and it pulls harder toward the tonic a fifth below. The rest of the chord stays the same dominant seventh.
What does ♭9 mean in a chord?
It means the ninth is lowered one semitone. In C, the ninth is D, so the flat nine is D♭. The flat nine is a minor second above the octave, and in jazz it gives a dominant chord a sharp, altered sound. The symbol is written after the seventh, as in C7♭9.
Is C7♭9 the same as C7♯9?
No. C7♭9 has D♭, a semitone above the root. C7♯9 has D♯, which is the same pitch as E♭ and sits a semitone below the major third. The two chords have different sounds and different uses, so the symbols are not interchangeable.