Chord · Bb Dominant 7♭9
B♭7♭9 Chord
B♭7♭9 is Bb, D, F, Ab and Cb — spicy V chord; minor-key resolution.
B♭7♭9 on every instrument
The same 5 notes, 2 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What B♭7♭9 is made of
Bb Dominant 7♭9 (Bb dominant 7♭9) is built from the notes Bb, D, F, Ab, Cb, with the interval pattern 1, 3, 5, b7, b9. A common dominant 7♭9 chord across many styles.
Stack 1, 3, 5, b7 and b9 on a root of B♭ and you get Bb, D, F, Ab and Cb. That interval recipe is what makes the chord a seventh flat nine chord — move the same shape to another root and the character travels with it, which is why C7♭9 sounds like a transposed B♭7♭9.
Dominant 7♭9: Spicy V chord; minor-key resolution.
Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with B♭ rather than its enharmonic equivalent.
Keys that contain B♭7♭9
No major or natural-minor key contains all 5 of these notes — this one gets borrowed.
Chords like this one sit outside the diatonic set — they arrive as secondary dominants, borrowed chords or passing harmony. Browse every key to see which progressions pull it in.
Other chords on B♭
Same root, different colour.
The same seventh flat nine shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Bb7b9
- What notes are in the Bb7b9 chord?
- Bb7b9 is made of Bb, D, F, Ab and Cb — the 1, 3, 5, b7 and b9 degrees of a seventh flat nine chord built on Bb.
- What keys use the Bb7b9 chord?
- No major or natural-minor key contains all 5 notes of Bb7b9. Chords like this arrive as borrowed harmony — secondary dominants, harmonic-minor colour, or chromatic passing chords — rather than as one of a key's native chords.
- How do you play Bb7b9 on guitar and piano?
- This page shows Bb7b9 on guitar and piano — 6 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
- Is Bb7b9 the same as A#7b9?
- Yes. Bb7b9 and A#7b9 are enharmonic — identical pitches written two different ways. Which spelling you use depends on the key you are in; Bb7b9 is the spelling this site treats as canonical.
Learn the theory behind it
Why B♭7♭9 behaves the way it does — the guides that explain the chord instead of just spelling it.