# C♯ Suspended 4th piano chord (C♯sus4)

C♯sus4 contains C♯, F♯ and G♯. The third replaced by the fourth. Every note is a black key.

- Canonical page: https://piano.org/chords/suspended-4th/c-sharp/
- Entity: chord:sus4:c-sharp
- Notes: C♯ F♯ G♯
- Formula: 1 4 5
- Intervals from root: P1, P4, P5
- Interval stack (semitones): 5 2
- Also written: C♯sus4, C#sus4, C♯ suspended 4th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

| Degree | Note | Interval from root | Semitones |
| --- | --- | --- | --- |
| 1 | C♯ | Perfect unison | 0 |
| 4 | F♯ | Perfect fourth | 5 |
| 5 | G♯ | Perfect fifth | 7 |

## Fingering

Rest your right hand over the notes with finger 1 on C♯, finger 3 on F♯, finger 5 on G♯. 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 | C♯ | C♯3 F♯3 G♯3 | 5/3 | 7 st, 96 mm |
| First inversion (C♯sus4/F♯) | F♯ | F♯3 G♯3 C♯4 | 6/3 | 7 st, 96 mm |
| Second inversion (C♯sus4/G♯) | G♯ | G♯3 C♯4 F♯4 | 6/4 | 10 st, 138 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | C♯3 F♯3 G♯3 | 7 st, 96 mm | identical | none |
| Close, first inversion | F♯3 G♯3 C♯4 | 7 st, 96 mm | identical | none |
| Close, second inversion | G♯3 C♯4 F♯4 | 10 st, 138 mm | identical | none |
| Open, fifth on top | C♯2 G♯2 F♯3 | 17 st, 234 mm | identical | none |
| Root and third only | C♯3 F♯3 | 5 st, 69 mm | subset | omits G♯ |

## One-edit neighbors

| Becomes | Edit | Changes | Common tones |
| --- | --- | --- | --- |
| C♯7sus4 | 1 4 5 ♭7 | adds B | 3 |
| C♯ | 1 3 5 | F♯ becomes E♯ | 2 |
| C♯m | 1 ♭3 5 | F♯ becomes E | 2 |
| C♯sus2 | 1 2 5 | F♯ becomes D♯ | 2 |
| C♯maj7 | 1 3 5 7 | F♯ becomes E♯, B♯ | 2 |
| C♯7 | 1 3 5 ♭7 | F♯ becomes E♯, B | 2 |
| C♯m7 | 1 ♭3 5 ♭7 | F♯ becomes E, B | 2 |
| C♯mMaj7 | 1 ♭3 5 7 | F♯ becomes E, B♯ | 2 |
| C♯6 | 1 3 5 6 | F♯ becomes E♯, A♯ | 2 |
| C♯m6 | 1 ♭3 5 6 | F♯ becomes E, A♯ | 2 |
| C♯add9 | 1 3 5 9 | F♯ becomes E♯, D♯ | 2 |
| C♯dim | 1 ♭3 ♭5 | F♯, G♯ becomes E, G | 1 |

## Set theory

- Absolute pitch classes: {1, 6, 8}
- Relative pitch classes: [0, 5, 7]
- Normal order: [6, 8, 1]
- Prime form: (027)
- Forte number: 3-9
- Interval vector: <010020>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| C♯3 | 49 | 138.59 Hz |
| F♯3 | 54 | 185.00 Hz |
| G♯3 | 56 | 207.65 Hz |

## Questions and answers

### What notes are in C♯sus4?

C♯sus4 contains C♯, F♯ and G♯. The formula is 1, 4, 5.

### How do you play C♯sus4 on piano?

Play C♯, F♯ and G♯ together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. Every note is a black key.

### What are the inversions of C♯sus4?

3 positions: root position C♯ F♯ G♯, C♯sus4/F♯, C♯sus4/G♯.

### What is the difference between C♯sus4 and C♯7sus4?

Adds B. 3 of the notes are shared.

### What is an easy C♯sus4 for small hands?

The root and third only voicing, C♯3 F♯3, spans 5 semitones or about 69 mm.

### What are the frequencies of C♯sus4?

From C♯3 at A440 in 12-TET: 138.59, 185.00, 207.65 Hz.

### What is the set class of C♯sus4?

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

### How do I transpose C♯sus4 to another key?

Keep the 1, 4, 5 formula on the new root. Csus4 is C, F, G; D♭sus4 is D♭, G♭, A♭.

### Is D♭sus4 the same as C♯sus4?

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:sus4:c-sharp
Last reviewed: 2026-08-12