C9 chord
C dominant ninth. The dominant ninth chord: a dominant seventh with the ninth added. It is a bright, colourful dominant used in jazz, blues, soul and funk.
Click a note to hear it
- Notes
- C E G B♭ D
- Formula
- 1 3 5 ♭7 9
- Intervals
- P1 M3 P5 m7 M2
- Also written
- Cdom9
Notes in C9
C9 is spelled C E G B♭ D: five notes stacked from the root C.
| Note | Interval above C | 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 | C E G B♭ D | C9 | |
| First inversion | E G B♭ D C | C9/E | |
| Second inversion | G B♭ D C E | C9/G | |
| Third inversion | B♭ D C E G | C9/B♭ | |
| Fourth inversion | D C E G B♭ | C9/D |
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
C9 in standard tuning. The barre shapes below slide anywhere on the neck, so the same fingers give you every root. Strings run from the lowest (left) to the highest (right); X means do not play that string.
E-shape barre at fret 8
A-shape barre at fret 3
What it sounds like
C9 is C, E, G, B♭ and D: a dominant seventh with the ninth, D, added. The major third and minor seventh keep the dominant's tritone and its pull toward a tonic, and the ninth adds a bright colour above the octave. The ninth is a major second above the root, so it forms a second against the major third, which adds a little friction. The chord sounds richer and more open than a plain dominant seventh, while still pulling strongly toward its resolution.
How it is used
Dominant ninths sit on the fifth degree in major and minor keys, usually before a tonic. Jazz uses V9 in ii, V, I progressions and in blues. Soul and funk use dominant ninths on the chord that moves to the tonic, and the ninth is often held as a colour. Classical composers use the ninth on dominant chords less often than the plain seventh. The dominant ninth resolves like a dominant seventh, and the fifth is often omitted in performance.
How it is built
The dominant ninth is a root with a major third, a perfect fifth, a minor seventh and a major ninth, 0, 4, 7, 10 and 14 semitones above the root. Common symbols are C9, C7(9) and C7(add9). The ninth is a second above the octave, so it has the same pitch class as the second. Inversions place E, G, B♭ or D in the bass, as in C9/E and C9/B♭. The dominant ninth contains C7 with D added, so C7 is a subset of it.
Which keys contain C9
C9 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 C9
Scales that contain every note of the chord, so they can be played over it:
- C Mixolydian
- D natural minor
- E Locrian
- F major
- F melodic minor
- G melodic minor
- G Dorian
- A Phrygian
- B♭ Lydian
Other C chords
How to practise it
Play G9, which is G, B, D, F and A, then resolve it to C by moving A down to G, F down to E, and B up to C. Listen to the ninth fall to the fifth of C. Repeat the resolution with G7, which lacks the A, to hear what the ninth adds.
Further reading
- Chord Extensions Explained: Ninths, Elevenths and ThirteenthsJazz & Popular Harmony · 7 min
- Jazz Chord Voicings: Shell and Rootless Voicings ExplainedJazz & Popular Harmony · 7 min
- Chord Symbols Explained: Major, Minor, Seventh and Slash ChordsHarmony · 8 min
Questions
What notes are in a C9 chord?
C9 contains C, E, G, B♭, D. That is the root, third, fifth, seventh, ninth of the chord.
How do you spell C dominant ninth?
Stack the intervals P1, M3, P5, m7, M2 above C: C, E, G, B♭, D.
What other symbols mean C9?
Lead sheets also write it Cdom9. They are the same chord.
What is the difference between C7 and C9?
C7 is C, E, G and B♭. C9 adds D, the ninth, and keeps the same dominant seventh. The added note sits a major second above the octave, which makes the chord brighter and wider. C9 keeps the dominant pull and usually resolves to the same tonic as C7.
Is a ninth chord always a dominant chord?
No. A ninth can be added to a major seventh chord, as in Cmaj9, or to a minor seventh chord, as in Cm9. The dominant ninth is a dominant seventh with the ninth added and the minor seventh kept. The ninth is always a second above the octave, but the seventh decides the chord's type.
Do you need the fifth in a C9 chord?
No. The fifth is the least essential note in a dominant chord, and it is often left out in jazz voicings. The third, seventh and ninth define C9, so a voicing of E, B♭ and D over a C bass still names the chord. The root in the bass is often the only other note needed.