C Sixth-Ninth Chord

Chord Tones: C Sixth-Ninth Chord

Symbol: 6/9 — Formula: 1-3-5-6-9

Chord Notation

Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.

Inversions

Harmonic Function

The C sixth ninth chord commonly functions as the tonic (I) in C major/minor. Its harmonic role varies by key — in major keys it provides stable harmonic grounding.

The 6/9 chord adds both the sixth and ninth to a major triad without a seventh. It has a rich, colorful sound with a jazz and bossa nova flavor, often used as a final tonic chord. The C Sixth-Ninth Chord specifically contains 5 notes: C, E, G, A, D (formula: 1-3-5-6-9). On piano, C-rooted chords sit entirely on white keys in their basic triad form, making them the first chords most students learn. Pop, folk, and singer-songwriter music heavily use C-rooted chords because open-position guitar voicings and piano shapes are immediately accessible.

Common Progressions

The C Sixth-Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• I69-IVmaj7

Songs Featuring the Sixth-Ninth Chord

Well-known songs where the C Sixth-Ninth Chord — or this chord type — plays a prominent role:

• Chameleon – Herbie Hancock
• Mercy Mercy Mercy – Cannonball Adderley
• Four – Miles Davis

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the C Sixth-Ninth Chord

These scales include the C Sixth-Ninth Chord as a diatonic or characteristic chord: