# G♯ Half Diminished 7th piano chord (G♯m7♭5)

G♯m7♭5 contains G♯, B, D and F♯. A diminished triad with the minor seventh added on top. G♯ and F♯ are black keys; B and D are white.

- Canonical page: https://piano.org/chords/half-diminished/g-sharp/
- Entity: chord:half-diminished-7th:g-sharp
- Notes: G♯ B D F♯
- Formula: 1 ♭3 ♭5 ♭7
- Intervals from root: P1, m3, TT, m7
- Interval stack (semitones): 3 3 4
- Also written: G♯m7♭5, G#m7b5, G♯ half diminished 7th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

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

## Fingering

Rest your right hand over the notes with finger 2 on G♯, finger 3 on B, finger 4 on D, finger 5 on F♯. The left hand mirrors it.
Right hand 2-3-4-5, left hand 5-4-3-2. Source: piano.org fingering method v1.

## Inversions

| Position | Bass | Notes in order | Figured bass | Span |
| --- | --- | --- | --- | --- |
| Root position | G♯ | G♯3 B3 D4 F♯4 | 7 | 10 st, 138 mm |
| First inversion (G♯m7♭5/B) | B | B3 D4 F♯4 G♯4 | 6/5 | 9 st, 124 mm |
| Second inversion (G♯m7♭5/D) | D | D4 F♯4 G♯4 B4 | 4/3 | 9 st, 124 mm |
| Third inversion (G♯m7♭5/F♯) | F♯ | F♯4 G♯4 B4 D5 | 4/2 | 8 st, 110 mm |

## Voicings (10)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | G♯3 B3 D4 F♯4 | 10 st, 138 mm | identical | none |
| Close, first inversion | B3 D4 F♯4 G♯4 | 9 st, 124 mm | identical | none |
| Close, second inversion | D4 F♯4 G♯4 B4 | 9 st, 124 mm | identical | none |
| Close, third inversion | F♯4 G♯4 B4 D5 | 8 st, 110 mm | identical | none |
| Drop 2 | D3 G♯3 B3 F♯4 | 16 st, 220 mm | identical | none |
| Drop 3 | B2 G♯3 D4 F♯4 | 19 st, 261 mm | identical | none |
| Drop 2 and 4 | G♯2 D3 B3 F♯4 | 22 st, 303 mm | identical | none |
| Shell, root ♭7 ♭3 | G♯2 F♯3 B3 | 15 st, 206 mm | subset | omits D |
| Guide tones, ♭3 and ♭7 | B3 F♯4 | 7 st, 96 mm | subset | omits G♯ and D |
| Rootless close | B3 D4 F♯4 | 7 st, 96 mm | subset | omits G♯ |

## Diatonic function by key

| Key | Roman numeral | Function |
| --- | --- | --- |
| F♯ minor | iim7♭5 | Predominant |
| A major | viim7♭5 | Dominant function |

Classification system: common-practice functional harmony.

## Progressions (2)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| ii, v, i | F♯ minor | iim7♭5 | G♯m7♭5 to C♯m7 to F♯m7 | G♯m7♭5 opens the phrase |
| vii, I | A major | viim7♭5 | G♯m7♭5 to Amaj7 | G♯m7♭5 opens the phrase |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| G♯dim | 1 ♭3 ♭5 | drops F♯ | 3 |
| G♯m7 | 1 ♭3 5 ♭7 | D becomes D♯ | 3 |
| G♯dim7 | 1 ♭3 ♭5 ♭♭7 | F♯ becomes F | 3 |
| G♯m9 | 1 ♭3 5 ♭7 9 | D becomes D♯, A♯ | 3 |
| G♯m | 1 ♭3 5 | D, F♯ becomes D♯ | 2 |
| G♯7 | 1 3 5 ♭7 | B, D becomes B♯, D♯ | 2 |
| G♯mMaj7 | 1 ♭3 5 7 | D, F♯ becomes D♯, F× | 2 |
| G♯aug7 | 1 3 ♯5 ♭7 | B, D becomes B♯, D× | 2 |
| G♯7sus4 | 1 4 5 ♭7 | B, D becomes C♯, D♯ | 2 |
| G♯m6 | 1 ♭3 5 6 | D, F♯ becomes D♯, E♯ | 2 |

## Set theory

- Absolute pitch classes: {8, 11, 2, 6}
- Relative pitch classes: [0, 3, 6, 10]
- Normal order: [6, 8, 11, 2]
- Prime form: (0258)
- Forte number: 4-27
- Interval vector: <012111>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| G♯3 | 56 | 207.65 Hz |
| B3 | 59 | 246.94 Hz |
| D4 | 62 | 293.66 Hz |
| F♯4 | 66 | 369.99 Hz |

## Questions and answers

### What notes are in G♯m7♭5?

G♯m7♭5 contains G♯, B, D and F♯. The formula is 1, ♭3, ♭5, ♭7.

### How do you play G♯m7♭5 on piano?

Play G♯, B, D and F♯ together. Right hand fingers 2, 3, 4, 5; left hand 5, 4, 3, 2. G♯ and F♯ are black keys; B and D are white.

### What are the inversions of G♯m7♭5?

4 positions: root position G♯ B D F♯, G♯m7♭5/B, G♯m7♭5/D, G♯m7♭5/F♯.

### What keys contain G♯m7♭5?

2: iim7♭5 in F♯ minor, viim7♭5 in A major.

### What is the difference between G♯m7♭5 and G♯dim?

Drops F♯. 3 of the notes are shared.

### What is an easy G♯m7♭5 for small hands?

The guide tones, ♭3 and ♭7 voicing, B3 F♯4, spans 7 semitones or about 96 mm.

### What are the frequencies of G♯m7♭5?

From G♯3 at A440 in 12-TET: 207.65, 246.94, 293.66, 369.99 Hz.

### What is the set class of G♯m7♭5?

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

### How do I transpose G♯m7♭5 to another key?

Keep the 1, ♭3, ♭5, ♭7 formula on the new root. Cm7♭5 is C, E♭, G♭, B♭; C♯m7♭5 is C♯, E, G, B.

### Is A♭m7♭5 the same as G♯m7♭5?

Enharmonically yes: the same piano keys and the same sound, spelled differently.

## 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:g-sharp
Last reviewed: 2026-08-12