B♭ Augmented Seventh Chord

Chord Tones: B♭ Augmented Seventh Chord

Symbol: aug7, +7, 7♯5 — Formula: 1-3-♯5-♭7

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♭ augmented seventh 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 extended harmonic tension.

The augmented seventh chord adds a minor seventh to the augmented triad, combining the restlessness of an augmented fifth with the tension of a dominant seventh. Used for maximum harmonic tension. The B♭ Augmented Seventh Chord specifically contains 4 notes: B♭, D, G♭, A♭ (formula: 1-3-♯5-♭7). 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♭ Augmented Seventh Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• Vaug7-I
• Iaug7-IV

Songs Featuring the Augmented Seventh Chord

Well-known songs where the B♭ Augmented Seventh Chord — or this chord type — plays a prominent role:

• Whole Lotta Love – Led Zeppelin
• Come Together – Beatles (chord variant)
• Spanish Key – Miles Davis

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the B♭ Augmented Seventh Chord

These scales include the B♭ Augmented Seventh Chord as a diatonic or characteristic chord: