# A Suspended 4th piano chord (Asus4)

Asus4 contains A, D and E. The third replaced by the fourth. Every note is a white key.

- Canonical page: https://piano.org/chords/suspended-4th/a/
- Entity: chord:sus4:a
- Notes: A D E
- Formula: 1 4 5
- Intervals from root: P1, P4, P5
- Interval stack (semitones): 5 2
- Also written: Asus4, Asus4, A suspended 4th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

| Degree | Note | Interval from root | Semitones |
| --- | --- | --- | --- |
| 1 | A | Perfect unison | 0 |
| 4 | D | Perfect fourth | 5 |
| 5 | E | Perfect fifth | 7 |

## Fingering

Rest your right hand over the notes with finger 1 on A, finger 3 on D, 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 D4 E4 | 5/3 | 7 st, 96 mm |
| First inversion (Asus4/D) | D | D4 E4 A4 | 6/3 | 7 st, 96 mm |
| Second inversion (Asus4/E) | E | E4 A4 D5 | 6/4 | 10 st, 138 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | A3 D4 E4 | 7 st, 96 mm | identical | none |
| Close, first inversion | D4 E4 A4 | 7 st, 96 mm | identical | none |
| Close, second inversion | E4 A4 D5 | 10 st, 138 mm | identical | none |
| Open, fifth on top | A2 E3 D4 | 17 st, 234 mm | identical | none |
| Root and third only | A3 D4 | 5 st, 69 mm | subset | omits E |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| A7sus4 | 1 4 5 ♭7 | adds G | 3 |
| A | 1 3 5 | D becomes C♯ | 2 |
| Am | 1 ♭3 5 | D becomes C | 2 |
| Asus2 | 1 2 5 | D becomes B | 2 |
| Amaj7 | 1 3 5 7 | D becomes C♯, G♯ | 2 |
| A7 | 1 3 5 ♭7 | D becomes C♯, G | 2 |
| Am7 | 1 ♭3 5 ♭7 | D becomes C, G | 2 |
| AmMaj7 | 1 ♭3 5 7 | D becomes C, G♯ | 2 |
| A6 | 1 3 5 6 | D becomes C♯, F♯ | 2 |
| Am6 | 1 ♭3 5 6 | D becomes C, F♯ | 2 |
| Aadd9 | 1 3 5 9 | D becomes C♯, B | 2 |
| Adim | 1 ♭3 ♭5 | D, E becomes C, E♭ | 1 |

## Set theory

- Absolute pitch classes: {9, 2, 4}
- Relative pitch classes: [0, 5, 7]
- Normal order: [2, 4, 9]
- Prime form: (027)
- Forte number: 3-9
- Interval vector: <010020>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| A3 | 57 | 220.00 Hz |
| D4 | 62 | 293.66 Hz |
| E4 | 64 | 329.63 Hz |

## Questions and answers

### What notes are in Asus4?

Asus4 contains A, D and E. The formula is 1, 4, 5.

### How do you play Asus4 on piano?

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

### What are the inversions of Asus4?

3 positions: root position A D E, Asus4/D, Asus4/E.

### What is the difference between Asus4 and A7sus4?

Adds G. 3 of the notes are shared.

### What is an easy Asus4 for small hands?

The root and third only voicing, A3 D4, spans 5 semitones or about 69 mm.

### What are the frequencies of Asus4?

From A3 at A440 in 12-TET: 220.00, 293.66, 329.63 Hz.

### What is the set class of Asus4?

Prime form (027), Forte 3-9, interval vector &lt;010020&gt;.

### How do I transpose Asus4 to another key?

Keep the 1, 4, 5 formula on the new root. Csus4 is C, F, G; C♯sus4 is C♯, F♯, 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:sus4:a
Last reviewed: 2026-08-12