B♭ Major Ninth Chord

Chord Tones: B♭ Major Ninth Chord

Symbol: maj9, M9, △9 — Formula: 1-3-5-7-9

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 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. The B♭ Major Ninth Chord specifically contains 5 notes: B♭, D, F, A, C (formula: 1-3-5-7-9). 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♭ Major Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• Imaj9-IVmaj9
• Imaj9-ii7

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.

Scales Containing the B♭ Major Ninth Chord

These scales include the B♭ Major Ninth Chord as a diatonic or characteristic chord: