The C Half Diminished chord is a four-note chord made up of C, E♭, G♭, and B♭. It is built from a root, minor third, diminished fifth, and minor seventh.
Construction
C Half Diminished = Root + Minor 3rd + Diminished 5th + Minor 7th = C · E♭ · G♭ · B♭
| Note | Interval | Degree |
|---|---|---|
| C | Root | 1 |
| E♭ | Minor 3rd | ♭3 |
| G♭ | Diminished 5th | ♭5 |
| B♭ | Minor 7th | ♭7 |
C Half Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | C – E♭ – G♭ – B♭ |
| 1st Inversion | E♭ – G♭ – B♭ – C |
| 2nd Inversion | G♭ – B♭ – C – E♭ |
| 3rd Inversion | B♭ – C – E♭ – G♭ |
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 C 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 C Half Diminished sits diatonically across the common keys:
- In D♭ major, C Half Diminished is the vii° chord — the dominant.
- In B♭ minor, C Half Diminished is the ii° chord — a predominant.
Same Notes, Other Names
The notes C – E♭ – G♭ – B♭ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:
C Half Diminished — Frequently Asked Questions
What is the C Half Diminished chord on piano?
The C Half Diminished chord contains the notes C – E♭ – G♭ – B♭. On piano, play these notes together to sound the chord.
What notes are in the C Half Diminished chord?
Cm7b5 contains four notes: C (root), Eb (minor third), Gb (diminished fifth), and Bb (minor seventh). A diminished triad with a minor seventh — dark, moody, and tense.
How does Cm7b5 differ from Cdim7?
Cm7b5 has Bb (minor seventh). Cdim7 has A (diminished seventh). Half-diminished is less tense than fully diminished — the minor seventh softens it slightly.
How does Cm7b5 differ from Cm7?
Cm7b5 has Gb (diminished fifth). Cm7 has G (perfect fifth). The flatted fifth adds significant tension and darkness.
How is Cm7b5 used in music?
Cm7b5 is the ii chord in Bb minor jazz harmony (Cm7b5–F7–Bbm). It is essential for minor-key ii–V–i progressions. Also the vii chord in Db Major.
What songs use Half Diminished chords?
Half-diminished chords are essential in jazz minor-key harmony. Autumn Leaves uses the ii°7–V7–i in G minor. Still Crazy After All These Years (Paul Simon) features half-diminished harmony.
Is Cm7b5 the same as Ebm6?
Same four notes (C, Eb, Gb, Bb = Eb, Gb, Bb, C). Context determines the name: Cm7b5 when C is root, Ebm6 when Eb is root.