B♭ Sixth-Ninth Chord
Chord Tones: B♭ Sixth-Ninth Chord
Symbol: 6/9 — Formula: 1-3-5-6-9
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | B♭4 | 466.164 Hz |
| 3 | D4 | 293.665 Hz |
| 5 | F4 | 349.228 Hz |
| 6 | G4 | 391.995 Hz |
| 9 | C4 | 261.626 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | B♭6/9 |
| All Common Symbols | 6/9 |
| Interval Formula | 1-3-5-6-9 |
| Harmonic Category | bright |
Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.
Inversions
| Inversion | Notes (low to high) | Bass Note | Slash Notation |
|---|---|---|---|
| Root Position | B♭4 – D4 – F4 – G4 – C4 | B♭ | B♭ Sixth-Ninth Chord |
| First Inversion | D4 – F4 – G4 – C4 – B♭4 | D | B♭ Sixth-Ninth Chord/D |
| Second Inversion | F4 – G4 – C4 – B♭4 – D4 | F | B♭ Sixth-Ninth Chord/F |
| Third Inversion | G4 – C4 – B♭4 – D4 – F4 | G | B♭ Sixth-Ninth Chord/G |
| Fourth Inversion | C4 – B♭4 – D4 – F4 – G4 | C | B♭ Sixth-Ninth Chord/C |
Harmonic Function
The B♭ sixth ninth chord commonly functions as the subtonic (♭VII) in C major or subdominant in F 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 B♭ Sixth-Ninth Chord specifically contains 5 notes: B♭, D, F, G, C (formula: 1-3-5-6-9). On piano, Bb-rooted chords start on a black key and create hand shapes that jazz pianists find ideal for voicing seventh chords and extended harmonies. Jazz standards, swing, and big band charts are heavily weighted toward Bb because it allows horn sections to play in their most comfortable range.
Common Progressions
The B♭ Sixth-Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
Songs Featuring the Sixth-Ninth Chord
Well-known songs where the B♭ 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.
| Note | Equal Temp. | Pythagorean | Just Intonation |
|---|---|---|---|
| B♭4 | 466.164 Hz | 463.538 Hz | 470.926 Hz |
| D4 | 293.665 Hz | 293.332 Hz | 294.329 Hz |
| F4 | 349.228 Hz | 347.654 Hz | 348.834 Hz |
| G4 | 391.995 Hz | 391.111 Hz | 392.438 Hz |
| C4 | 261.626 Hz | 260.740 Hz | 261.626 Hz |
Scales Containing the B♭ Sixth-Ninth Chord
These scales include the B♭ Sixth-Ninth Chord as a diatonic or characteristic chord: