Chord · C Dominant 7♭9
C7♭9 Chord
C7♭9 is C, E, G, Bb and Db — spicy V chord; minor-key resolution.
C7♭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 C7♭9 is made of
C7b9 (C seventh flat nine) is built from the notes C, E, G, Bb, Db, with the interval pattern 1, 3, 5, b7, b9.
Stack 1, 3, 5, b7 and b9 on a root of C and you get C, E, G, Bb and Db. 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 D7♭9 sounds like a transposed C7♭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 C7♭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 C
Same root, different colour.
The same seventh flat nine shape, moved
The identical interval recipe, built on other roots.
Questions people ask about C7b9
- What notes are in the C7b9 chord?
- C7b9 is made of C, E, G, Bb and Db — the 1, 3, 5, b7 and b9 degrees of a seventh flat nine chord built on C.
- What keys use the C7b9 chord?
- No major or natural-minor key contains all 5 notes of C7b9. 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 C7b9 on guitar and piano?
- This page shows C7b9 on guitar and piano — 6 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
Learn the theory behind it
Why C7♭9 behaves the way it does — the guides that explain the chord instead of just spelling it.