# A Major piano chord (A)

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

- Canonical page: https://piano.org/chords/major/a/
- Entity: chord:major:a
- 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 | A3 C♯4 E4 | 5/3 | 7 st, 96 mm |
| First inversion (A/C♯) | C♯ | C♯4 E4 A4 | 6/3 | 8 st, 110 mm |
| Second inversion (A/E) | E | E4 A4 C♯5 | 6/4 | 9 st, 124 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | A3 C♯4 E4 | 7 st, 96 mm | identical | none |
| Close, first inversion | C♯4 E4 A4 | 8 st, 110 mm | identical | none |
| Close, second inversion | E4 A4 C♯5 | 9 st, 124 mm | identical | none |
| Open, fifth on top | A2 E3 C♯4 | 16 st, 220 mm | identical | none |
| Root and third only | A3 C♯4 | 4 st, 55 mm | subset | omits E |

## Diatonic function by key

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

Classification system: common-practice functional harmony.

## Progressions (8)

| Progression | Key | Role | Sequence | Voice leading |
| --- | --- | --- | --- | --- |
| ♭VI, iv, i, v | C♯ minor | ♭VI | A to F♯m to C♯m to G♯m | A opens the phrase |
| i, ♭VI | C♯ minor | ♭VI | C♯m to A | 2 tones held from C♯m |
| V, I | D major | V | A to D | A opens the phrase |
| ii, V, I | D major | V | Em to A to D | 1 tone held from Em |
| IV, V, I | E major | IV | A to B to E | A opens the phrase |
| I, IV | E major | IV | E to A | 1 tone held from E |
| ♭III, ♭VI, ii°, v | F♯ minor | ♭III | A to D to G♯dim to C♯m | A opens the phrase |
| i, ♭III | F♯ minor | ♭III | F♯m to A | 2 tones held from F♯m |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| Amaj7 | 1 3 5 7 | adds G♯ | 3 |
| A7 | 1 3 5 ♭7 | adds G | 3 |
| A6 | 1 3 5 6 | adds F♯ | 3 |
| Aadd9 | 1 3 5 9 | adds B | 3 |
| Am | 1 ♭3 5 | C♯ becomes C | 2 |
| Aaug | 1 3 ♯5 | E becomes E♯ | 2 |
| Asus2 | 1 2 5 | C♯ becomes B | 2 |
| Asus4 | 1 4 5 | C♯ becomes D | 2 |
| Am7 | 1 ♭3 5 ♭7 | C♯ becomes C, G | 2 |
| AmMaj7 | 1 ♭3 5 7 | C♯ becomes C, G♯ | 2 |
| Aaug7 | 1 3 ♯5 ♭7 | E becomes E♯, G | 2 |
| A7sus4 | 1 4 5 ♭7 | C♯ becomes D, G | 2 |

## Set theory

- Absolute pitch classes: {9, 1, 4}
- Relative pitch classes: [0, 4, 7]
- Normal order: [9, 1, 4]
- Prime form: (037)
- Forte number: 3-11
- Interval vector: <001110>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| A3 | 57 | 220.00 Hz |
| C♯4 | 61 | 277.18 Hz |
| E4 | 64 | 329.63 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. C♯ is a black key; A 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: ♭VI in C♯ minor, V in D major, IV in E major, ♭III in F♯ minor, I in A major, ♭VII in B minor.

### What is the difference between A and Amaj7?

Adds G♯. 3 of the notes are shared.

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

The root and third only voicing, A3 C♯4, spans 4 semitones or about 55 mm.

### What are the frequencies of A?

From A3 at A440 in 12-TET: 220.00, 277.18, 329.63 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♯.

## 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
Last reviewed: 2026-08-12