The B♭ Augmented 7th chord is a four-note chord made up of B♭, D, F♯, and A♭. It is built from a root, major third, augmented fifth, and minor seventh.
Construction
B♭ Augmented 7th = Root + Major 3rd + Minor 6th + Minor 7th = B♭ · D · F♯ · A♭
| Note | Interval | Degree |
|---|---|---|
| B♭ | Root | 1 |
| D | Major 3rd | 3 |
| F♯ | Minor 6th | ♯5 |
| A♭ | Minor 7th | ♭7 |
B♭ Augmented 7th Inversions
| Position | Notes |
|---|---|
| Root Position | B♭ – D – F♯ – A♭ |
| 1st Inversion | D – F♯ – A♭ – B♭ |
| 2nd Inversion | F♯ – A♭ – B♭ – D |
| 3rd Inversion | A♭ – B♭ – D – F♯ |
Key Signature
A Augmented 7th chord is built from symmetrical or ambiguous intervals, so it doesn’t belong to a single key and has no key signature of its own.
Same Notes, Other Names
The notes B♭ – D – F♯ – A♭ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:
B♭ Augmented 7th — Frequently Asked Questions
What is the B♭ Augmented 7th chord on piano?
The B♭ Augmented 7th chord contains the notes B♭ – D – F♯ – A♭. On piano, play these notes together to sound the chord.
What notes are in the Bb Augmented 7th chord?
The Bb Augmented 7th chord (Bb+7) contains four notes: Bb (root), D (major third), F# (augmented fifth), and Ab (minor seventh). It combines an augmented triad with a minor seventh.
How does Bb Augmented 7th differ from Bb Dominant 7th?
Both contain Bb, D, and Ab. Bb+7 has F# (augmented fifth) while Bb7 has F (perfect fifth). The raised fifth adds extra tension and chromatic pull.
How is Bb Augmented 7th used in music?
Bb+7 is an altered dominant resolving to Eb Major. The F# pulls up to G while Ab pulls down to G — converging on the third of Eb. Eb is a common jazz and brass key, making Bb+7 a frequently used altered dominant.
What genres use Augmented 7th chords?
Augmented 7th chords are common in jazz, gospel, blues, and R&B. Bb+7 appears frequently in jazz because Eb Major is one of the most common jazz keys.
What songs use Augmented 7th chords?
Augmented 7th chords appear in jazz standards and gospel. Bb+7 resolves to Eb Major, appearing in many big band and jazz ensemble charts.
What is the difference between +7 and 7#5?
They are the same chord. Bb+7, Bb7#5, and Bbaug7 all refer to Bb Augmented 7th.