A Sixth-Ninth Chord

Chord Tones: A 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 A sixth ninth chord commonly functions as the submediant (vi) in C major or dominant (V) in D major. 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 A Sixth-Ninth Chord specifically contains 5 notes: A, C♯, E, F♯, B (formula: 1-3-5-6-9). On guitar, A-rooted chords anchor to the open A string (5th string), and barre chord shapes rooted on A form the basis of the "A-shape" CAGED system. Blues, rock, and country music use A-rooted chords extensively — the classic 12-bar blues often starts on A, and many rock power chord riffs center on the open A string.

Common Progressions

The A 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 A 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 A Sixth-Ninth Chord

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