A°7 — A, C, E♭, G♭ — is the vii°7 of B♭ minor and an enharmonic equivalent of F♯°7, C°7, and E♭°7. The chord lives most naturally inside flat-side keys (B♭ minor, D♭ major) where its three flats integrate cleanly into the surrounding signature.
Intervals
The A diminished 7 chord stacks two thirds on the root. Each interval and its size in semitones:
- A→Cminor 3rd3 semitones
- C→Ebminor 3rd3 semitones
- Eb→Gbdiminished 7th9 semitones
On the keyboard
Each note of the A diminished 7 chord highlighted on a piano. Pitch class is what matters — any octave works.
On the guitar
One voicing of the A diminished 7 chord on a six-string guitar fretboard.
Common mistakes
A°7's seventh is G♭, enharmonic to F♯. Inside flat-key context the G♭ spelling preserves consistency. In jazz lead-sheet practice, the chord is sometimes written A°7 with F♯ as the seventh — strictly incorrect by the seven-letter rule, but common.
In context
A°7 → B♭ minor is the leading-tone cadence in B♭ minor. The chord also appears in D♭ major as a borrowed harmony from the parallel D♭ minor. In jazz, A°7 substitutes for F7♭9 (a tritone-related dominant) in certain D-minor or D♭-major progressions.
Drill it
The A diminished 7 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.
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Frequently asked
- What notes are in an A diminished 7 chord?
- A°7 contains four notes: A (root), C (minor third), E♭ (diminished fifth), and G♭ (diminished seventh — same pitch as F♯).
- How does A°7 resolve?
- In B♭ minor: A rises to B♭, C holds or rises to D♭, E♭ holds, G♭ falls to F. Every voice moves by half-step or whole-step.
- Is A°7 the same as F♯°7?
- Enharmonically yes — same four pitches in different inversions. A°7 is the flat-side spelling; F♯°7 is the sharp-side. Composers pick one based on surrounding harmony.
- Where does A°7 appear in music?
- In B♭-minor cadences (where it's the proper local spelling), in chromatically-modulating music as a pivot chord, and as a tritone substitute in jazz dominant cycles.