# B Half Diminished 7th piano chord (Bm7♭5)

Bm7♭5 contains B, D, F and A. A diminished triad with the minor seventh added on top. Every note is a white key.

- Canonical page: https://piano.org/chords/half-diminished/b/
- Entity: chord:half-diminished-7th:b
- Notes: B D F A
- Formula: 1 ♭3 ♭5 ♭7
- Intervals from root: P1, m3, TT, m7
- Interval stack (semitones): 3 3 4
- Also written: Bm7♭5, Bm7b5, B half diminished 7th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

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

## Fingering

Rest your right hand over the notes with finger 1 on B, finger 2 on D, finger 3 on F, finger 5 on A. 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 | B | B3 D4 F4 A4 | 7 | 10 st, 138 mm |
| First inversion (Bm7♭5/D) | D | D4 F4 A4 B4 | 6/5 | 9 st, 124 mm |
| Second inversion (Bm7♭5/F) | F | F4 A4 B4 D5 | 4/3 | 9 st, 124 mm |
| Third inversion (Bm7♭5/A) | A | A4 B4 D5 F5 | 4/2 | 8 st, 110 mm |

## Voicings (10)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | B3 D4 F4 A4 | 10 st, 138 mm | identical | none |
| Close, first inversion | D4 F4 A4 B4 | 9 st, 124 mm | identical | none |
| Close, second inversion | F4 A4 B4 D5 | 9 st, 124 mm | identical | none |
| Close, third inversion | A4 B4 D5 F5 | 8 st, 110 mm | identical | none |
| Drop 2 | F3 B3 D4 A4 | 16 st, 220 mm | identical | none |
| Drop 3 | D3 B3 F4 A4 | 19 st, 261 mm | identical | none |
| Drop 2 and 4 | B2 F3 D4 A4 | 22 st, 303 mm | identical | none |
| Shell, root ♭7 ♭3 | B2 A3 D4 | 15 st, 206 mm | subset | omits F |
| Guide tones, ♭3 and ♭7 | D4 A4 | 7 st, 96 mm | subset | omits B and F |
| Rootless close | D4 F4 A4 | 7 st, 96 mm | subset | omits B |

## Diatonic function by key

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

Classification system: common-practice functional harmony.

## Progressions (2)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| vii, I | C major | viim7♭5 | Bm7♭5 to Cmaj7 | Bm7♭5 opens the phrase |
| ii, v, i | A minor | iim7♭5 | Bm7♭5 to Em7 to Am7 | Bm7♭5 opens the phrase |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| Bdim | 1 ♭3 ♭5 | drops A | 3 |
| Bm7 | 1 ♭3 5 ♭7 | F becomes F♯ | 3 |
| Bdim7 | 1 ♭3 ♭5 ♭♭7 | A becomes A♭ | 3 |
| Bm9 | 1 ♭3 5 ♭7 9 | F becomes F♯, C♯ | 3 |
| Bm | 1 ♭3 5 | F, A becomes F♯ | 2 |
| B7 | 1 3 5 ♭7 | D, F becomes D♯, F♯ | 2 |
| BmMaj7 | 1 ♭3 5 7 | F, A becomes F♯, A♯ | 2 |
| Baug7 | 1 3 ♯5 ♭7 | D, F becomes D♯, F× | 2 |
| B7sus4 | 1 4 5 ♭7 | D, F becomes E, F♯ | 2 |
| Bm6 | 1 ♭3 5 6 | F, A becomes F♯, G♯ | 2 |

## Set theory

- Absolute pitch classes: {11, 2, 5, 9}
- Relative pitch classes: [0, 3, 6, 10]
- Normal order: [9, 11, 2, 5]
- Prime form: (0258)
- Forte number: 4-27
- Interval vector: <012111>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| B3 | 59 | 246.94 Hz |
| D4 | 62 | 293.66 Hz |
| F4 | 65 | 349.23 Hz |
| A4 | 69 | 440.00 Hz |

## Questions and answers

### What notes are in Bm7♭5?

Bm7♭5 contains B, D, F and A. The formula is 1, ♭3, ♭5, ♭7.

### How do you play Bm7♭5 on piano?

Play B, D, F and A together. Right hand fingers 1, 2, 3, 5; left hand 5, 3, 2, 1. Every note is a white key.

### What are the inversions of Bm7♭5?

4 positions: root position B D F A, Bm7♭5/D, Bm7♭5/F, Bm7♭5/A.

### What keys contain Bm7♭5?

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

### What is the difference between Bm7♭5 and Bdim?

Drops A. 3 of the notes are shared.

### What is an easy Bm7♭5 for small hands?

The guide tones, ♭3 and ♭7 voicing, D4 A4, spans 7 semitones or about 96 mm.

### What are the frequencies of Bm7♭5?

From B3 at A440 in 12-TET: 246.94, 293.66, 349.23, 440.00 Hz.

### What is the set class of Bm7♭5?

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

### How do I transpose Bm7♭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 C♭m7♭5 the same as Bm7♭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:b
Last reviewed: 2026-08-12