Chords
C Half-diminished
C · Eb · Gb · Bb
The half-diminished seventh — a diminished triad with a minor seventh. The ii of a minor key.
Also written Cø · Cø7 · C-7b5 · Ch7 · Ch
C Half-diminished
C · Eb · Gb · Bb
Voicings on the piano
| Voicing | Notes | Play it on your instrument |
|---|---|---|
| Closed, root position | C3 · Eb3 · Gb3 · Bb3 | |
| Open (drop 2) | Gb2 · C3 · Eb3 · Bb3 | |
| Shell | C3 · Eb3 · Bb3 | |
| Rootless | Eb3 · Gb3 · Bb3 · C4 |
Tap a key or a fret to hear it.
Anatomy
C Half-diminished (Cm7b5) contains the notes C · Eb · Gb · Bb, each with a role measured as an interval from the root.
Read on: how triads are built · seventh chords
Inversions
An inversion of C Half-diminished puts a chord tone other than C in the bass; the name after the slash is that bass note.
Where it lives
The keys and the scales C Half-diminished belongs to.
In which keys
C Half-diminished is diatonic to 3 keys; the numeral is its degree and the label its harmonic function.
Scales that contain it
C Half-diminished fits inside these scales, each built on C.
- C Minor BluesC · Eb · F · Gb · G · Bb
- C LocrianC · Db · Eb · F · Gb · Ab · Bb
- C AlteredC · Db · D# · E · F# · Ab · Bb
- C Half-Whole DiminishedC · Db · Eb · E · F# · G · A · Bb
- C Locrian PentatonicC · Eb · F · Gb · Bb
- C Super Locrian PentatonicC · Eb · Fb · Gb · Bb
- C Locrian #2C · D · Eb · F · Gb · Ab · Bb
- C Locrian 6C · Db · Eb · F · Gb · A · Bb
Understanding the C Half-diminished chord
Names and symbols
Cm7b5 is the chord symbol for C Half-diminished; it is also written Cø, Cø7, C-7b5, Ch7, Ch.
The half-diminished seventh is written m7♭5 on charts and ø7 (or just ø) in jazz notation; both name the same four notes. It is not the diminished seventh, °7, whose seventh is a semitone lower.
How it is built
On C it is C · Eb · Gb · Bb, stacking 1P · 3m · 5d · 7m. It is written m7♭5 or with the ø symbol, and both mean the same thing: a diminished triad softened by a minor rather than a diminished seventh.
How it is used
It is the ii of a minor ii–V–i, which makes it one of the most frequently played chords in jazz despite sounding exotic in isolation. It is also the chord built on the seventh degree of a major scale.
Unlike the fully diminished seventh it is not symmetrical, so it has a clear home and a clear direction: down a fifth, to the dominant.
Learn this properly
Chapter 10: Chords: Triads and SeventhsCommon questions
- What notes are in Cm7b5?
- Cm7b5 contains C · Eb · Gb · Bb. Name any set of notes with the chord identifier.
- What is the difference between half-diminished and fully diminished?
- The seventh. Half-diminished uses a minor seventh; fully diminished lowers it again to a diminished seventh, which makes the chord symmetrical.
- Where is a half-diminished chord used?
- As the ii of a minor ii–V–i, and as the chord built on the seventh degree of a major scale.
- What notes are in the C Half-diminished chord?
- The C Half-diminished chord contains the notes C · Eb · Gb · Bb: the root C with the intervals 1P, 3m, 5d, 7m stacked above it. Play them together for the chord or one after another for an arpeggio. The lowest note is normally C, but any chord tone can take the bass in an inversion.
- What intervals make up the C Half-diminished chord?
- Measured from C, the C Half-diminished chord stacks the intervals 1P, 3m, 5d, 7m. The quality of the third and of the seventh, if there is one, is what gives the chord its character; the rest of the notes colour it. Every interval in the formula links to its own page, with its sound.