B♭ Diminished Seventh Chord
Chord Tones: B♭ Diminished Seventh Chord
Symbol: dim7, °7 — Formula: 1-♭3-♭5-𝄫7
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | B♭4 | 466.164 Hz |
| ♭3 | D♭4 | 277.183 Hz |
| ♭5 | E4 | 329.628 Hz |
| 𝄫7 | G4 | 391.995 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | B♭dim7 |
| All Common Symbols | dim7, °7 |
| Interval Formula | 1-♭3-♭5-𝄫7 |
| Harmonic Category | tense |
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 – D♭4 – E4 – G4 | B♭ | B♭ Diminished Seventh Chord |
| First Inversion | D♭4 – E4 – G4 – B♭4 | D♭ | B♭ Diminished Seventh Chord/D♭ |
| Second Inversion | E4 – G4 – B♭4 – D♭4 | E | B♭ Diminished Seventh Chord/E |
| Third Inversion | G4 – B♭4 – D♭4 – E4 | G | B♭ Diminished Seventh Chord/G |
Harmonic Function
The B♭ diminished seventh 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 extended harmonic tension.
The diminished seventh chord consists of four equally-spaced minor thirds, creating a symmetrical, highly dissonant chord. It is used as a dramatic pivot chord and in chromatic passing harmony. The B♭ Diminished Seventh Chord specifically contains 4 notes: B♭, D♭, E, G (formula: 1-♭3-♭5-𝄫7). 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♭ Diminished Seventh Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
Songs Featuring the Diminished Seventh Chord
Well-known songs where the B♭ Diminished Seventh Chord — or this chord type — plays a prominent role:
- While My Guitar Gently Weeps – Beatles
- Georgia on My Mind – Ray Charles
- Sophisticated Lady – Duke Ellington
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 |
| D♭4 | 277.183 Hz | 278.437 Hz | 279.067 Hz |
| E4 | 329.628 Hz | 330.001 Hz | 327.032 Hz |
| G4 | 391.995 Hz | 391.111 Hz | 392.438 Hz |
Scales Containing the B♭ Diminished Seventh Chord
These scales include the B♭ Diminished Seventh Chord as a diatonic or characteristic chord: