Bb Major Ninth Chord
Chord Tones: Bb Major Ninth Chord
Symbol: maj9, M9, △9 — Formula: 1-3-5-7-9
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | Bb | 466.164 Hz |
| 3 | D | 293.665 Hz |
| 5 | F | 349.228 Hz |
| 7 | A | 440.000 Hz |
| 9 | C | 261.626 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | Bbmaj9 |
| 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 | Bb – D – F – A – C | Bb | Bb Major Ninth Chord |
| First Inversion | D – F – A – C – Bb | D | Bb Major Ninth Chord/D |
| Second Inversion | F – A – C – Bb – D | F | Bb Major Ninth Chord/F |
| Third Inversion | A – C – Bb – D – F | A | Bb Major Ninth Chord/A |
| Fourth Inversion | C – Bb – D – F – A | C | Bb Major Ninth Chord/C |
Harmonic Function
The Bb 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 Bb Major Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
Imaj9-IVmaj9Imaj9-ii9
Songs Featuring the Major Ninth Chord
Well-known songs where the Bb 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 |
|---|---|---|---|
| Bb | 466.164 Hz | 463.538 Hz | 470.926 Hz |
| D | 293.665 Hz | 293.332 Hz | 294.329 Hz |
| F | 349.228 Hz | 347.654 Hz | 348.834 Hz |
| A | 440.000 Hz | 440.000 Hz | 436.043 Hz |
| C | 261.626 Hz | 260.740 Hz | 261.626 Hz |
Scales Containing the Bb Major Ninth Chord
These scales include the Bb Major Ninth Chord as a diatonic or characteristic chord: