# B♭ Suspended 4th piano chord (B♭sus4)

B♭sus4 contains B♭, E♭ and F. The third replaced by the fourth. B♭ and E♭ are black keys; F is white.

- Canonical page: https://piano.org/chords/suspended-4th/b-flat/
- Entity: chord:sus4:b-flat
- Notes: B♭ E♭ F
- Formula: 1 4 5
- Intervals from root: P1, P4, P5
- Interval stack (semitones): 5 2
- Also written: B♭sus4, Bbsus4, B♭ suspended 4th
- Parameters: A440, 12-TET, 165 mm octave, spans centre to centre

## Construction

| Degree | Note | Interval from root | Semitones |
| --- | --- | --- | --- |
| 1 | B♭ | Perfect unison | 0 |
| 4 | E♭ | Perfect fourth | 5 |
| 5 | F | Perfect fifth | 7 |

## Fingering

Rest your right hand over the notes with finger 1 on B♭, finger 3 on E♭, finger 5 on F. 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 | B♭ | B♭3 E♭4 F4 | 5/3 | 7 st, 96 mm |
| First inversion (B♭sus4/E♭) | E♭ | E♭4 F4 B♭4 | 6/3 | 7 st, 96 mm |
| Second inversion (B♭sus4/F) | F | F4 B♭4 E♭5 | 6/4 | 10 st, 138 mm |

## Voicings (5)

| Voicing | Notes | Span | Relation | Omits or adds |
| --- | --- | --- | --- | --- |
| Close, root position | B♭3 E♭4 F4 | 7 st, 96 mm | identical | none |
| Close, first inversion | E♭4 F4 B♭4 | 7 st, 96 mm | identical | none |
| Close, second inversion | F4 B♭4 E♭5 | 10 st, 138 mm | identical | none |
| Open, fifth on top | B♭2 F3 E♭4 | 17 st, 234 mm | identical | none |
| Root and third only | B♭3 E♭4 | 5 st, 69 mm | subset | omits F |

## One-edit neighbors

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

## Set theory

- Absolute pitch classes: {10, 3, 5}
- Relative pitch classes: [0, 5, 7]
- Normal order: [3, 5, 10]
- Prime form: (027)
- Forte number: 3-9
- Interval vector: <010020>

## Frequencies (close root position)

| Note | MIDI | Frequency |
| --- | --- | --- |
| B♭3 | 58 | 233.08 Hz |
| E♭4 | 63 | 311.13 Hz |
| F4 | 65 | 349.23 Hz |

## Questions and answers

### What notes are in B♭sus4?

B♭sus4 contains B♭, E♭ and F. The formula is 1, 4, 5.

### How do you play B♭sus4 on piano?

Play B♭, E♭ and F together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. B♭ and E♭ are black keys; F is white.

### What are the inversions of B♭sus4?

3 positions: root position B♭ E♭ F, B♭sus4/E♭, B♭sus4/F.

### What is the difference between B♭sus4 and B♭7sus4?

Adds A♭. 3 of the notes are shared.

### What is an easy B♭sus4 for small hands?

The root and third only voicing, B♭3 E♭4, spans 5 semitones or about 69 mm.

### What are the frequencies of B♭sus4?

From B♭3 at A440 in 12-TET: 233.08, 311.13, 349.23 Hz.

### What is the set class of B♭sus4?

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

### How do I transpose B♭sus4 to another key?

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

### Is A♯sus4 the same as B♭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:b-flat
Last reviewed: 2026-08-12