B♭ Suspended 4th Chord
Chord Tones: B♭ Suspended 4th Chord
Symbol: sus4, sus — Formula: 1-4-5
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | B♭4 | 466.164 Hz |
| 4 | E♭4 | 311.127 Hz |
| 5 | F4 | 349.228 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | B♭sus4 |
| All Common Symbols | sus4, sus |
| Interval Formula | 1-4-5 |
| Harmonic Category | open |
Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.
Inversions
| Inversion | Notes (low to high) | Bass Note | Slash Notation |
|---|---|---|---|
| Root Position | B♭4 – E♭4 – F4 | B♭ | B♭ Suspended 4th Chord |
| First Inversion | E♭4 – F4 – B♭4 | E♭ | B♭ Suspended 4th Chord/E♭ |
| Second Inversion | F4 – B♭4 – E♭4 | F | B♭ Suspended 4th Chord/F |
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.
Common Progressions
The B♭ Suspended 4th Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
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.
| Note | Equal Temp. | Pythagorean | Just Intonation |
|---|---|---|---|
| B♭4 | 466.164 Hz | 463.538 Hz | 470.926 Hz |
| E♭4 | 311.127 Hz | 309.026 Hz | 313.951 Hz |
| F4 | 349.228 Hz | 347.654 Hz | 348.834 Hz |
Scales Containing the B♭ Suspended 4th Chord
These scales include the B♭ Suspended 4th Chord as a diatonic or characteristic chord: