C9 — C, E, G, B♭, D — is a dominant 9th chord: major triad + minor 7th + major 9th — a dominant chord with the 9th added on top for a rich, slightly bluesy colour.
Intervals
The C dominant 9 chord stacks two thirds on the root. Each interval and its size in semitones:
- C→Emajor 3rd4 semitones
- E→Gminor 3rd3 semitones
- G→Bbminor 3rd3 semitones
- Bb→Dmajor 3rd4 semitones
On the keyboard
Each note of the C dominant 9 chord highlighted on a piano. Pitch class is what matters — any octave works.
On the guitar
One voicing of the C dominant 9 chord on a six-string guitar fretboard.
- 1C
- 3E
- 5G
- ♭7Bb
- 9D
Common mistakes
The defining note is the 9th (D). It sits more than an octave above the root, which is why the chord needs a wide voicing — in tight piano voicings the 9th usually appears in the top register while the root and lower triad tones cluster below.
In context
Functions as the V9 in its target key — a richer, more colourful alternative to the plain V7 dominant.
Drill it
The C dominant 9 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.
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Frequently asked
- What notes are in a C9 chord?
- C9 contains five notes: C, E, G, B♭, D.
- How is C9 different from C7?
- C9 adds the 9th (D) on top of the underlying 7th chord. The 9th extends the chord into the next octave and adds harmonic colour.
- When is C9 used in music?
- Functions as the V9 in its target key — a richer, more colourful alternative to the plain V7 dominant.