# A♯ Augmented piano chord (A♯aug)

A♯aug contains A♯, C× and E×. Two stacked major thirds. A♯ and E× are black keys; C× is white.

- Canonical page: https://piano.org/chords/augmented/a-sharp/
- Entity: chord:augmented:a-sharp
- Notes: A♯ C× E×
- Formula: 1 3 ♯5
- Intervals from root: P1, M3, m6
- Interval stack (semitones): 4 4
- Also written: A♯aug, A#aug, A♯ augmented
- 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× | Major third | 4 |
| ♯5 | E× | Minor sixth | 8 |

## Fingering

Rest your right hand over the notes with finger 1 on A♯, finger 3 on C×, finger 5 on E×. 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 | A♯ | A♯3 C×4 E×4 | 5/3 | 8 st, 110 mm |
| First inversion (A♯aug/C×) | C× | C×4 E×4 A♯4 | 6/3 | 8 st, 110 mm |
| Second inversion (A♯aug/E×) | E× | E×4 A♯4 C×5 | 6/4 | 8 st, 110 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | A♯3 C×4 E×4 | 8 st, 110 mm | identical | none |
| Close, first inversion | C×4 E×4 A♯4 | 8 st, 110 mm | identical | none |
| Close, second inversion | E×4 A♯4 C×5 | 8 st, 110 mm | identical | none |
| Open, fifth on top | A♯2 E×3 C×4 | 16 st, 220 mm | identical | none |
| Root and third only | A♯3 C×4 | 4 st, 55 mm | subset | omits E× |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| A♯aug7 | 1 3 ♯5 ♭7 | adds G♯ | 3 |
| A♯ | 1 3 5 | E× becomes E♯ | 2 |
| A♯maj7 | 1 3 5 7 | E× becomes E♯, G× | 2 |
| A♯7 | 1 3 5 ♭7 | E× becomes E♯, G♯ | 2 |
| A♯6 | 1 3 5 6 | E× becomes E♯, F× | 2 |
| A♯add9 | 1 3 5 9 | E× becomes E♯, B♯ | 2 |
| A♯m | 1 ♭3 5 | C×, E× becomes C♯, E♯ | 1 |
| A♯dim | 1 ♭3 ♭5 | C×, E× becomes C♯, E | 1 |
| A♯sus2 | 1 2 5 | C×, E× becomes B♯, E♯ | 1 |
| A♯sus4 | 1 4 5 | C×, E× becomes D♯, E♯ | 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 |
| --- | --- | --- |
| A♯3 | 58 | 233.08 Hz |
| C×4 | 62 | 293.66 Hz |
| E×4 | 66 | 369.99 Hz |

## Questions and answers

### What notes are in A♯aug?

A♯aug contains A♯, C× and E×. The formula is 1, 3, ♯5.

### How do you play A♯aug on piano?

Play A♯, C× and E× together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. A♯ and E× are black keys; C× is white.

### What are the inversions of A♯aug?

3 positions: root position A♯ C× E×, A♯aug/C×, A♯aug/E×.

### What is the difference between A♯aug and A♯aug7?

Adds G♯. 3 of the notes are shared.

### What is an easy A♯aug for small hands?

The root and third only voicing, A♯3 C×4, spans 4 semitones or about 55 mm.

### What are the frequencies of A♯aug?

From A♯3 at A440 in 12-TET: 233.08, 293.66, 369.99 Hz.

### What is the set class of A♯aug?

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

### How do I transpose A♯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 B♭aug the same as A♯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:a-sharp
Last reviewed: 2026-08-12