# A♯ Major piano chord (A♯)

A♯ contains A♯, C× and E♯. A major third with a perfect fifth above the root. A♯ is a black key; C× and E♯ are white.

- Canonical page: https://piano.org/chords/major/a-sharp/
- Entity: chord:major:a-sharp
- Notes: A♯ C× E♯
- Formula: 1 3 5
- Intervals from root: P1, M3, P5
- Interval stack (semitones): 4 3
- Also written: A♯, A#, A♯ major
- 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♯ | Perfect fifth | 7 |

## 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 | 7 st, 96 mm |
| First inversion (A♯/C×) | C× | C×4 E♯4 A♯4 | 6/3 | 8 st, 110 mm |
| Second inversion (A♯/E♯) | E♯ | E♯4 A♯4 C×5 | 6/4 | 9 st, 124 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | A♯3 C×4 E♯4 | 7 st, 96 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 | 9 st, 124 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♯ |

## Diatonic function by key

| Key | Roman numeral | Function |
| --- | --- | --- |
| C minor | ♭VII | Subtonic |
| D minor | ♭VI | Pre-dominant color |
| E♭ major | V | Dominant, wants to resolve |
| F major | IV | Subdominant, away from home |
| G minor | ♭III | Relative-major color |
| B♭ major | I | Tonic, home |

Classification system: common-practice functional harmony.

## Progressions (7)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| ♭VII, i | C minor | ♭VII | B♭ to Cm | A♯ opens the phrase |
| ♭VI, iv, i, v | D minor | ♭VI | B♭ to Gm to Dm to Am | A♯ opens the phrase |
| i, ♭VI | D minor | ♭VI | Dm to B♭ | 2 tones held from Dm |
| V, I | E♭ major | V | B♭ to E♭ | A♯ opens the phrase |
| ii, V, I | E♭ major | V | Fm to B♭ to E♭ | 1 tone held from Fm |
| IV, V, I | F major | IV | B♭ to C to F | A♯ opens the phrase |
| I, IV | F major | IV | F to B♭ | 1 tone held from F |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| A♯maj7 | 1 3 5 7 | adds G× | 3 |
| A♯7 | 1 3 5 ♭7 | adds G♯ | 3 |
| A♯6 | 1 3 5 6 | adds F× | 3 |
| A♯add9 | 1 3 5 9 | adds B♯ | 3 |
| A♯m | 1 ♭3 5 | C× becomes C♯ | 2 |
| A♯aug | 1 3 ♯5 | E♯ becomes E× | 2 |
| A♯sus2 | 1 2 5 | C× becomes B♯ | 2 |
| A♯sus4 | 1 4 5 | C× becomes D♯ | 2 |
| A♯m7 | 1 ♭3 5 ♭7 | C× becomes C♯, G♯ | 2 |
| A♯mMaj7 | 1 ♭3 5 7 | C× becomes C♯, G× | 2 |
| A♯aug7 | 1 3 ♯5 ♭7 | E♯ becomes E×, G♯ | 2 |
| A♯7sus4 | 1 4 5 ♭7 | C× becomes D♯, G♯ | 2 |

## Set theory

- Absolute pitch classes: {10, 2, 5}
- Relative pitch classes: [0, 4, 7]
- Normal order: [10, 2, 5]
- Prime form: (037)
- Forte number: 3-11
- Interval vector: <001110>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| A♯3 | 58 | 233.08 Hz |
| C×4 | 62 | 293.66 Hz |
| E♯4 | 65 | 349.23 Hz |

## Questions and answers

### What notes are in A♯?

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

### How do you play A♯ on piano?

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

### What are the inversions of A♯?

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

### What keys contain A♯?

6: ♭VII in C minor, ♭VI in D minor, V in E♭ major, IV in F major, ♭III in G minor, I in B♭ major.

### What is the difference between A♯ and A♯maj7?

Adds G×. 3 of the notes are shared.

### What is an easy A♯ 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♯?

From A♯3 at A440 in 12-TET: 233.08, 293.66, 349.23 Hz.

### What is the set class of A♯?

Prime form (037), Forte 3-11, interval vector &lt;001110&gt;.

### How do I transpose A♯ to another key?

Keep the 1, 3, 5 formula on the new root. C is C, E, G; C♯ is C♯, E♯, G♯.

### Is B♭ the same as A♯?

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:major:a-sharp
Last reviewed: 2026-08-12