# C Half Diminished 7th piano chord (Cm7♭5)

Cm7♭5 contains C, E♭, G♭ and B♭. A diminished triad with the minor seventh added on top. E♭, G♭ and B♭ are black keys; C is white.

- Canonical page: https://piano.org/chords/half-diminished/c/
- Entity: chord:half-diminished-7th:c
- Notes: C E♭ G♭ B♭
- Formula: 1 ♭3 ♭5 ♭7
- Intervals from root: P1, m3, TT, m7
- Interval stack (semitones): 3 3 4
- Also written: Cm7♭5, Cm7b5, C half diminished 7th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

| Degree | Note | Interval from root | Semitones |
| --- | --- | --- | --- |
| 1 | C | Perfect unison | 0 |
| ♭3 | E♭ | Minor third | 3 |
| ♭5 | G♭ | Tritone | 6 |
| ♭7 | B♭ | Minor seventh | 10 |

## Fingering

Rest your right hand over the notes with finger 1 on C, finger 2 on E♭, finger 3 on G♭, finger 5 on B♭. The left hand mirrors it.
Right hand 1-2-3-5, left hand 5-3-2-1. Source: piano.org fingering method v1.

## Inversions

| Position | Bass | Notes in order | Figured bass | Span |
| --- | --- | --- | --- | --- |
| Root position | C | C3 E♭3 G♭3 B♭3 | 7 | 10 st, 138 mm |
| First inversion (Cm7♭5/E♭) | E♭ | E♭3 G♭3 B♭3 C4 | 6/5 | 9 st, 124 mm |
| Second inversion (Cm7♭5/G♭) | G♭ | G♭3 B♭3 C4 E♭4 | 4/3 | 9 st, 124 mm |
| Third inversion (Cm7♭5/B♭) | B♭ | B♭3 C4 E♭4 G♭4 | 4/2 | 8 st, 110 mm |

## Voicings (10)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | C3 E♭3 G♭3 B♭3 | 10 st, 138 mm | identical | none |
| Close, first inversion | E♭3 G♭3 B♭3 C4 | 9 st, 124 mm | identical | none |
| Close, second inversion | G♭3 B♭3 C4 E♭4 | 9 st, 124 mm | identical | none |
| Close, third inversion | B♭3 C4 E♭4 G♭4 | 8 st, 110 mm | identical | none |
| Drop 2 | G♭2 C3 E♭3 B♭3 | 16 st, 220 mm | identical | none |
| Drop 3 | E♭2 C3 G♭3 B♭3 | 19 st, 261 mm | identical | none |
| Drop 2 and 4 | C2 G♭2 E♭3 B♭3 | 22 st, 303 mm | identical | none |
| Shell, root ♭7 ♭3 | C2 B♭2 E♭3 | 15 st, 206 mm | subset | omits G♭ |
| Guide tones, ♭3 and ♭7 | E♭3 B♭3 | 7 st, 96 mm | subset | omits C and G♭ |
| Rootless close | E♭3 G♭3 B♭3 | 7 st, 96 mm | subset | omits C |

## Diatonic function by key

| Key | Roman numeral | Function |
| --- | --- | --- |
| D♭ major | viim7♭5 | Dominant function |
| B♭ minor | iim7♭5 | Predominant |

Classification system: common-practice functional harmony.

## Progressions (2)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| vii, I | D♭ major | viim7♭5 | Cm7♭5 to D♭maj7 | Cm7♭5 opens the phrase |
| ii, v, i | B♭ minor | iim7♭5 | Cm7♭5 to Fm7 to B♭m7 | Cm7♭5 opens the phrase |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| Cdim | 1 ♭3 ♭5 | drops B♭ | 3 |
| Cm7 | 1 ♭3 5 ♭7 | G♭ becomes G | 3 |
| Cdim7 | 1 ♭3 ♭5 ♭♭7 | B♭ becomes B♭♭ | 3 |
| Cm9 | 1 ♭3 5 ♭7 9 | G♭ becomes G, D | 3 |
| Cm | 1 ♭3 5 | G♭, B♭ becomes G | 2 |
| C7 | 1 3 5 ♭7 | E♭, G♭ becomes E, G | 2 |
| CmMaj7 | 1 ♭3 5 7 | G♭, B♭ becomes G, B | 2 |
| Caug7 | 1 3 ♯5 ♭7 | E♭, G♭ becomes E, G♯ | 2 |
| C7sus4 | 1 4 5 ♭7 | E♭, G♭ becomes F, G | 2 |
| Cm6 | 1 ♭3 5 6 | G♭, B♭ becomes G, A | 2 |

## Set theory

- Absolute pitch classes: {0, 3, 6, 10}
- Relative pitch classes: [0, 3, 6, 10]
- Normal order: [10, 0, 3, 6]
- Prime form: (0258)
- Forte number: 4-27
- Interval vector: <012111>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| C3 | 48 | 130.81 Hz |
| E♭3 | 51 | 155.56 Hz |
| G♭3 | 54 | 185.00 Hz |
| B♭3 | 58 | 233.08 Hz |

## Questions and answers

### What notes are in Cm7♭5?

Cm7♭5 contains C, E♭, G♭ and B♭. The formula is 1, ♭3, ♭5, ♭7.

### How do you play Cm7♭5 on piano?

Play C, E♭, G♭ and B♭ together. Right hand fingers 1, 2, 3, 5; left hand 5, 3, 2, 1. E♭, G♭ and B♭ are black keys; C is white.

### What are the inversions of Cm7♭5?

4 positions: root position C E♭ G♭ B♭, Cm7♭5/E♭, Cm7♭5/G♭, Cm7♭5/B♭.

### What keys contain Cm7♭5?

2: viim7♭5 in D♭ major, iim7♭5 in B♭ minor.

### What is the difference between Cm7♭5 and Cdim?

Drops B♭. 3 of the notes are shared.

### What is an easy Cm7♭5 for small hands?

The guide tones, ♭3 and ♭7 voicing, E♭3 B♭3, spans 7 semitones or about 96 mm.

### What are the frequencies of Cm7♭5?

From C3 at A440 in 12-TET: 130.81, 155.56, 185.00, 233.08 Hz.

### What is the set class of Cm7♭5?

Prime form (0258), Forte 4-27, interval vector &lt;012111&gt;.

### How do I transpose Cm7♭5 to another key?

Keep the 1, ♭3, ♭5, ♭7 formula on the new root. C♯m7♭5 is C♯, E, G, B; Dm7♭5 is D, F, A♭, C.

## Provenance

Every derived value above is computed by the piano.org theory kernel from the root, the quality and the stated parameters. Nothing is hand-entered per chord.

Machine record: https://piano.org/api/knowledge/v1/entities/chord:half-diminished-7th:c
Last reviewed: 2026-08-12