B♭ Major Ninth Chord
Chord Tones: B♭ Major Ninth Chord
Symbol: maj9, M9, △9 — Formula: 1-3-5-7-9
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | B♭4 | 466.164 Hz |
| 3 | D4 | 293.665 Hz |
| 5 | F4 | 349.228 Hz |
| 7 | A4 | 440.000 Hz |
| 9 | C4 | 261.626 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | B♭maj9 |
| All Common Symbols | maj9, M9, △9 |
| Interval Formula | 1-3-5-7-9 |
| Harmonic Category | lush |
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 – A4 – C4 | B♭ | B♭ Major Ninth Chord |
| First Inversion | D4 – F4 – A4 – C4 – B♭4 | D | B♭ Major Ninth Chord/D |
| Second Inversion | F4 – A4 – C4 – B♭4 – D4 | F | B♭ Major Ninth Chord/F |
| Third Inversion | A4 – C4 – B♭4 – D4 – F4 | A | B♭ Major Ninth Chord/A |
| Fourth Inversion | C4 – B♭4 – D4 – F4 – A4 | C | B♭ Major Ninth Chord/C |
Harmonic Function
The B♭ major 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 major ninth chord extends the major seventh with a ninth, creating a lush, sophisticated sound central to jazz and R&B. It conveys spaciousness, warmth, and harmonic richness.
Common Progressions
The B♭ Major Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
Songs Featuring the Major Ninth Chord
Well-known songs where the B♭ Major Ninth Chord — or this chord type — plays a prominent role:
- Nights in White Satin – Moody Blues
- Clair de Lune – Debussy (adapted)
- Once in a While – jazz standard
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 |
| A4 | 440.000 Hz | 440.000 Hz | 436.043 Hz |
| C4 | 261.626 Hz | 260.740 Hz | 261.626 Hz |
Scales Containing the B♭ Major Ninth Chord
These scales include the B♭ Major Ninth Chord as a diatonic or characteristic chord: