# A Half Diminished 7th piano chord (Am7♭5)

Am7♭5 contains A, C, E♭ and G. A diminished triad with the minor seventh added on top. E♭ is a black key; A, C and G are white.

- Canonical page: https://piano.org/chords/half-diminished/a/
- Entity: chord:half-diminished-7th:a
- Notes: A C E♭ G
- Formula: 1 ♭3 ♭5 ♭7
- Intervals from root: P1, m3, TT, m7
- Interval stack (semitones): 3 3 4
- Also written: Am7♭5, Am7b5, A half diminished 7th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

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

## Fingering

Rest your right hand over the notes with finger 1 on A, finger 2 on C, finger 3 on E♭, finger 5 on G. 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 | A | A3 C4 E♭4 G4 | 7 | 10 st, 138 mm |
| First inversion (Am7♭5/C) | C | C4 E♭4 G4 A4 | 6/5 | 9 st, 124 mm |
| Second inversion (Am7♭5/E♭) | E♭ | E♭4 G4 A4 C5 | 4/3 | 9 st, 124 mm |
| Third inversion (Am7♭5/G) | G | G4 A4 C5 E♭5 | 4/2 | 8 st, 110 mm |

## Voicings (10)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | A3 C4 E♭4 G4 | 10 st, 138 mm | identical | none |
| Close, first inversion | C4 E♭4 G4 A4 | 9 st, 124 mm | identical | none |
| Close, second inversion | E♭4 G4 A4 C5 | 9 st, 124 mm | identical | none |
| Close, third inversion | G4 A4 C5 E♭5 | 8 st, 110 mm | identical | none |
| Drop 2 | E♭3 A3 C4 G4 | 16 st, 220 mm | identical | none |
| Drop 3 | C3 A3 E♭4 G4 | 19 st, 261 mm | identical | none |
| Drop 2 and 4 | A2 E♭3 C4 G4 | 22 st, 303 mm | identical | none |
| Shell, root ♭7 ♭3 | A2 G3 C4 | 15 st, 206 mm | subset | omits E♭ |
| Guide tones, ♭3 and ♭7 | C4 G4 | 7 st, 96 mm | subset | omits A and E♭ |
| Rootless close | C4 E♭4 G4 | 7 st, 96 mm | subset | omits A |

## Diatonic function by key

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

Classification system: common-practice functional harmony.

## Progressions (2)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| ii, v, i | G minor | iim7♭5 | Am7♭5 to Dm7 to Gm7 | Am7♭5 opens the phrase |
| vii, I | B♭ major | viim7♭5 | Am7♭5 to B♭maj7 | Am7♭5 opens the phrase |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| Adim | 1 ♭3 ♭5 | drops G | 3 |
| Am7 | 1 ♭3 5 ♭7 | E♭ becomes E | 3 |
| Adim7 | 1 ♭3 ♭5 ♭♭7 | G becomes G♭ | 3 |
| Am9 | 1 ♭3 5 ♭7 9 | E♭ becomes E, B | 3 |
| Am | 1 ♭3 5 | E♭, G becomes E | 2 |
| A7 | 1 3 5 ♭7 | C, E♭ becomes C♯, E | 2 |
| AmMaj7 | 1 ♭3 5 7 | E♭, G becomes E, G♯ | 2 |
| Aaug7 | 1 3 ♯5 ♭7 | C, E♭ becomes C♯, E♯ | 2 |
| A7sus4 | 1 4 5 ♭7 | C, E♭ becomes D, E | 2 |
| Am6 | 1 ♭3 5 6 | E♭, G becomes E, F♯ | 2 |

## Set theory

- Absolute pitch classes: {9, 0, 3, 7}
- Relative pitch classes: [0, 3, 6, 10]
- Normal order: [7, 9, 0, 3]
- Prime form: (0258)
- Forte number: 4-27
- Interval vector: <012111>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| A3 | 57 | 220.00 Hz |
| C4 | 60 | 261.63 Hz |
| E♭4 | 63 | 311.13 Hz |
| G4 | 67 | 392.00 Hz |

## Questions and answers

### What notes are in Am7♭5?

Am7♭5 contains A, C, E♭ and G. The formula is 1, ♭3, ♭5, ♭7.

### How do you play Am7♭5 on piano?

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

### What are the inversions of Am7♭5?

4 positions: root position A C E♭ G, Am7♭5/C, Am7♭5/E♭, Am7♭5/G.

### What keys contain Am7♭5?

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

### What is the difference between Am7♭5 and Adim?

Drops G. 3 of the notes are shared.

### What is an easy Am7♭5 for small hands?

The guide tones, ♭3 and ♭7 voicing, C4 G4, spans 7 semitones or about 96 mm.

### What are the frequencies of Am7♭5?

From A3 at A440 in 12-TET: 220.00, 261.63, 311.13, 392.00 Hz.

### What is the set class of Am7♭5?

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

### How do I transpose Am7♭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.

## 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:a
Last reviewed: 2026-08-12