C dominant ninth
How to play C9 — Dominant ninth
C9 (Dominant ninth)C · E · G · B♭ · D
Piano samples: Salamander Grand Piano (CC-BY 3.0)
C dominant ninth — notes and structure
The C9 chord is a dominant seventh with the ninth added — funky and bluesy.
The C9 dominant ninth consists of the notes C, E, G, B♭, D. Its interval structure is R–3–5–7–9 — the root, then each chord tone stacked above it. This is the same chord you see in the interactive finder above, drawn on the piano keyboard with the root circled and every chord tone labelled.
C9 stacks a major third (E), a perfect fifth (G), a minor seventh (B♭) and a ninth (D) above the root C.
To play C9, press the keys C, E, G, B♭, D together — the root C is circled on the interactive keyboard above.
What key is C9 in?
Every note of C9 belongs to the scales below, so the chord sounds at home in each of these keys — the roman numeral is the degree it sits on.
- F major — the V chord
- D minor — the VII chord
Chords that go with C9
In F major, the chords built on the first, fourth and fifth degrees carry most songs — put C9 next to these:
Frequently asked questions
- What notes are in the C dominant ninth chord on piano?
- The C9 chord is made of the notes C, E, G, B♭, D. It is a dominant seventh with the ninth added — funky and bluesy.
- How do you play C dominant ninth on the piano?
- Press C, E, G, B♭, D at the same time, with the root C as the lowest note. The interactive keyboard above lights up the exact keys.
- What is the dominant ninth chord formula?
- Its interval structure is R–3–5–7–9 above the root — the same shape transposed to any of the twelve keys.
- What key does C9 belong to?
- C9 fits F major (where it is the V chord), D minor (where it is the VII chord) — every note of the chord is in those scales.