B♭ Suspended 4th Chord

Chord Tones: B♭ Suspended 4th Chord

Symbol: sus4, sus — Formula: 1-4-5

Chord Notation

Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.

Inversions

Harmonic Function

The B♭ sus4 chord commonly functions as the subtonic (♭VII) in C major or subdominant in F major. Its harmonic role varies by key — in major keys it provides stable harmonic grounding.

The sus4 chord replaces the third with a perfect fourth, creating tension that traditionally resolves down to the major third. It creates anticipation and is common before dominant chords. The B♭ Suspended 4th Chord specifically contains 3 notes: B♭, E♭, F (formula: 1-4-5). On piano, Bb-rooted chords start on a black key and create hand shapes that jazz pianists find ideal for voicing seventh chords and extended harmonies. Jazz standards, swing, and big band charts are heavily weighted toward Bb because it allows horn sections to play in their most comfortable range.

Common Progressions

The B♭ Suspended 4th Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• Vsus4-V-I
• Isus4-I

Songs Featuring the Suspended 4th Chord

Well-known songs where the B♭ Suspended 4th Chord — or this chord type — plays a prominent role:

• Scarborough Fair – Simon & Garfunkel
• The Seeker – The Who
• Born on the Bayou – CCR

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the B♭ Suspended 4th Chord

These scales include the B♭ Suspended 4th Chord as a diatonic or characteristic chord: