Skip to content
piano.org
A piano reference: chords, scales, theory. Full MIDI.

B♭ Suspended 4th

Notes: B♭ - E♭ - F | Degrees: 1 - 4 - 5 | Written: B♭sus4, B♭sus

Construction: Root, Perfect 4th, Perfect 5th

It is a chord where the third is suspended and raised to the perfect fourth, giving it a tense, unresolved sound that naturally wants to resolve to the major third

Fingering: RH 2-3-5, LH 5-3-2

Inversions: Root B♭sus4 - 1st B♭sus4/E♭ - 2nd B♭sus4/F

A♯ Suspended 4th
This is the same chord as A♯ Suspended 4th: the same keys on the keyboard, spelled with sharps.
Related boards
B♭sus47 st, 96.0 mmRoot position, figured bass 5/3

B♭3, E♭4, F4

Fingerings

Root position: either hand, fingers low note to high
HandNotesFingers
RightB♭, E♭, F1-3-5
LeftB♭, E♭, F5-3-1

Close-position standard fingering: either hand takes the whole shape. Thumb is 1, little finger is 5.

B♭ Suspended 4th: notes and degrees

B♭sus4 contains B♭, E♭ and F. The third replaced by the fourth.

Scale degree, note, and interval measured from the root.
DegreeNoteInterval from rootSemitones
1B♭Perfect unison0
4E♭Perfect fourth5
5FPerfect fifth7

B♭ and E♭ are black keys; F is white.

Construction

B♭ Suspended 4th = Root + Perfect 4th + Perfect 5th = B♭, E♭, F
NoteIntervalDegree
B♭Root1
E♭Perfect 4th4
FPerfect 5th5

Fingering

NoteKey colorRight handLeft hand
B♭blackthumb (1)little finger (5)
E♭blackmiddle finger (3)middle finger (3)
Fwhitelittle finger (5)thumb (1)

Right hand: thumb (1) on B♭, middle finger (3) on E♭, little finger (5) on F.

Left hand: little finger (5) on B♭, middle finger (3) on E♭, thumb (1) on F.

B♭ Suspended 4th Inversions

  • Root position
    B♭ – E♭ – F
  • 1st inversion (B♭sus4/E♭)
    E♭ – F – B♭
  • 2nd inversion (B♭sus4/F)
    F – B♭ – E♭

Key Signature

A Suspended 4th chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.

Chords in the Key of B♭ Major

These are the triads built on each degree of B♭ Major:

C1C2C3C4C5DFC6C7C8B♭
I — B♭ Major (major)
DegreeNumeralChordQuality
1IB♭ MajorMajor
2iiC MinorMinor
3iiiD MinorMinor
4IVE♭ MajorMajor
5VF MajorMajor
6viG MinorMinor
7vii°A DiminishedDiminished

Scales That Include the B♭ Suspended 4th

Same Notes, Other Names

The notes B♭ – E♭ – F aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:

B♭ Suspended 4th : Frequently Asked Questions

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 <010020>.
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.

B♭ Suspended 4th in detail

Exact

Every pitch class is present and nothing outside the chord is added.

TypeNotesSemitonesSpanOmissions and additionsSet relationFit
Close, root positionB♭3 E♭4 F4796 mmnoneidentical
Close, first inversionE♭4 F4 B♭4796 mmnoneidentical
Close, second inversionF4 B♭4 E♭510138 mmnoneidentical
Open, fifth on topB♭2 F3 E♭417234 mmnoneidentical

Reduced

A subset of the pitch classes: the identity is incomplete rather than altered.

TypeNotesSemitonesSpanOmissions and additionsSet relationFit
Root and third onlyB♭3 E♭4569 mmomits Fsubset

Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).

Change one note

Chords a single note away, and what moving that note does.

ChordChangeFormulaCommon tones
B♭7sus4adds A♭1 4 5 ♭73
B♭E♭ becomes D1 3 52
B♭mE♭ becomes D♭1 ♭3 52
B♭sus2E♭ becomes C1 2 52
B♭maj7E♭ becomes D, A1 3 5 72
B♭7E♭ becomes D, A♭1 3 5 ♭72
B♭m7E♭ becomes D♭, A♭1 ♭3 5 ♭72
B♭mMaj7E♭ becomes D♭, A1 ♭3 5 72
B♭6E♭ becomes D, G1 3 5 62
B♭m6E♭ becomes D♭, G1 ♭3 5 62
B♭add9E♭ becomes D, C1 3 5 92
B♭dimE♭, F becomes D♭, F♭1 ♭3 ♭51

Frequencies

NoteMIDIFrequency
B♭358233.08 Hz
E♭463311.13 Hz
F465349.23 Hz

Reference pitch A440, 12-TET, close root position.

Set theory: prime form, Forte number, interval vector
Absolute pitch class set
{10, 3, 5}
Normal order
[3, 5, 10]
Prime form
(027)
Forte number
3-9
Interval vector
<010020>
PairIntervalSemitonesInterval class
B♭ to E♭Perfect fourth55
B♭ to FPerfect fifth75
E♭ to FMajor second22

Where these facts come from

Every value on this page is derived from the note formula for a suspended 4th applied to the root B♭, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.

References and further reading

The visible claims on this chord page are grounded in these verified sources.

  1. 1. Arthur Foote and Walter R. Spalding (1905)

    Modern Harmony in its Theory and Practice, Sections 170-173, chords of the eleventh and thirteenth, pp. 179-181; suspension p. 200; figured bass pp. 49, 84, 186

    Public domain treatise

  2. 2. Ferruccio Busoni (1911)

    Sketch of a New Esthetic of Music, The 113 seven-tone scales, p. 29

    Public domain treatise

  3. 3. Carl E. Gardner (1912)

    Essentials of Music Theory, Elementary volume

    Public domain treatise

  4. 4. piano.org

    piano.org chord note dataset: 43 chord types × 18 keys, derived from interval construction rules

    Primary data