The A Half Diminished chord is a four-note chord made up of A, C, E♭, and G. It is built from a root, minor third, diminished fifth, and minor seventh.
Construction
A Half Diminished = Root + Minor 3rd + Diminished 5th + Minor 7th = A · C · E♭ · G
| Note | Interval | Degree |
|---|---|---|
| A | Root | 1 |
| C | Minor 3rd | ♭3 |
| E♭ | Diminished 5th | ♭5 |
| G | Minor 7th | ♭7 |
A Half Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | A – C – E♭ – G |
| 1st Inversion | C – E♭ – G – A |
| 2nd Inversion | E♭ – G – A – C |
| 3rd Inversion | G – A – C – E♭ |
Key Signature
A Half Diminished 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.
How A Half Diminished functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where A Half Diminished sits diatonically across the common keys:
- In B♭ major, A Half Diminished is the vii° chord — the dominant.
- In G minor, A Half Diminished is the ii° chord — a predominant.
Same Notes, Other Names
The notes A – C – E♭ – G aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:
A Half Diminished — Frequently Asked Questions
What is the A Half Diminished chord on piano?
The A Half Diminished chord contains the notes A – C – E♭ – G. On piano, play these notes together to sound the chord.
What notes are in the A Half Diminished chord?
Am7b5 contains: A, C, Eb, G. Diminished triad with minor seventh.
How does Am7b5 differ from Adim7?
Minor seventh (G) vs diminished seventh (Gb).
How is Am7b5 used?
ii chord in G minor (Am7b5–D7–Gm). Very common in jazz.
What songs use Half Diminished?
Autumn Leaves uses Am7b5 in G minor. One of the most common half-diminished chords.
How does Am7b5 differ from Am7?
Flatted fifth (Eb vs E).
Is Am7b5 the same as Cm6?
Same four notes (A, C, Eb, G = C, Eb, G, A). Context determines the name.