# B♭ Augmented piano chord (B♭aug)

B♭aug contains B♭, D and F♯. Two stacked major thirds. B♭ and F♯ are black keys; D is white.

- Canonical page: https://piano.org/chords/augmented/b-flat/
- Entity: chord:augmented:b-flat
- Notes: B♭ D F♯
- Formula: 1 3 ♯5
- Intervals from root: P1, M3, m6
- Interval stack (semitones): 4 4
- Also written: B♭aug, Bbaug, B♭ augmented
- 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 | Major third | 4 |
| ♯5 | F♯ | Minor sixth | 8 |

## Fingering

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

## Inversions

| Position | Bass | Notes in order | Figured bass | Span |
| --- | --- | --- | --- | --- |
| Root position | B♭ | B♭3 D4 F♯4 | 5/3 | 8 st, 110 mm |
| First inversion (B♭aug/D) | D | D4 F♯4 B♭4 | 6/3 | 8 st, 110 mm |
| Second inversion (B♭aug/F♯) | F♯ | F♯4 B♭4 D5 | 6/4 | 8 st, 110 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | B♭3 D4 F♯4 | 8 st, 110 mm | identical | none |
| Close, first inversion | D4 F♯4 B♭4 | 8 st, 110 mm | identical | none |
| Close, second inversion | F♯4 B♭4 D5 | 8 st, 110 mm | identical | none |
| Open, fifth on top | B♭2 F♯3 D4 | 16 st, 220 mm | identical | none |
| Root and third only | B♭3 D4 | 4 st, 55 mm | subset | omits F♯ |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| B♭aug7 | 1 3 ♯5 ♭7 | adds A♭ | 3 |
| B♭ | 1 3 5 | F♯ becomes F | 2 |
| B♭maj7 | 1 3 5 7 | F♯ becomes F, A | 2 |
| B♭7 | 1 3 5 ♭7 | F♯ becomes F, A♭ | 2 |
| B♭6 | 1 3 5 6 | F♯ becomes F, G | 2 |
| B♭add9 | 1 3 5 9 | F♯ becomes F, C | 2 |
| B♭m | 1 ♭3 5 | D, F♯ becomes D♭, F | 1 |
| B♭dim | 1 ♭3 ♭5 | D, F♯ becomes D♭, F♭ | 1 |
| B♭sus2 | 1 2 5 | D, F♯ becomes C, F | 1 |
| B♭sus4 | 1 4 5 | D, F♯ becomes E♭, F | 1 |

## Set theory

- Absolute pitch classes: {10, 2, 6}
- Relative pitch classes: [0, 4, 8]
- Normal order: [2, 6, 10]
- Prime form: (048)
- Forte number: 3-12
- Interval vector: <000300>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| B♭3 | 58 | 233.08 Hz |
| D4 | 62 | 293.66 Hz |
| F♯4 | 66 | 369.99 Hz |

## Questions and answers

### What notes are in B♭aug?

B♭aug contains B♭, D and F♯. The formula is 1, 3, ♯5.

### How do you play B♭aug on piano?

Play B♭, D and F♯ together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. B♭ and F♯ are black keys; D is white.

### What are the inversions of B♭aug?

3 positions: root position B♭ D F♯, B♭aug/D, B♭aug/F♯.

### What is the difference between B♭aug and B♭aug7?

Adds A♭. 3 of the notes are shared.

### What is an easy B♭aug for small hands?

The root and third only voicing, B♭3 D4, spans 4 semitones or about 55 mm.

### What are the frequencies of B♭aug?

From B♭3 at A440 in 12-TET: 233.08, 293.66, 369.99 Hz.

### What is the set class of B♭aug?

Prime form (048), Forte 3-12, interval vector &lt;000300&gt;.

### How do I transpose B♭aug to another key?

Keep the 1, 3, ♯5 formula on the new root. Caug is C, E, G♯; D♭aug is D♭, F, A.

### Is A♯aug the same as B♭aug?

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:augmented:b-flat
Last reviewed: 2026-08-12