The B Diminished chord is a three-note chord made up of B, D, and F. It is built from a root, minor third, and diminished fifth.
Construction
B Diminished = Root + Minor 3rd + Diminished 5th = B · D · F
| Note | Interval | Degree |
|---|---|---|
| B | Root | 1 |
| D | Minor 3rd | ♭3 |
| F | Diminished 5th | ♭5 |
B Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | B – D – F |
| 1st Inversion | D – F – B |
| 2nd Inversion | F – B – D |
Key Signature
A Diminished 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.
How B Diminished functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where B Diminished sits diatonically across the common keys:
- In C major, B Diminished is the vii° chord — the dominant.
- In A minor, B Diminished is the ii° chord — a predominant.
B Diminished — Frequently Asked Questions
What is the B Diminished chord on piano?
The B Diminished chord contains the notes B – D – F. On piano, play these notes together to sound the chord.
What notes are in the B Diminished chord?
The B Diminished chord contains: B (root), D (minor third), and F (diminished fifth). Both intervals are compressed: the minor third is 3 semitones above the root, and the diminished fifth is 6 semitones — a tritone.
How does B Diminished differ from B Minor?
B Minor has a perfect fifth. B Diminished lowers the fifth by one semitone to F (diminished fifth). That extra compression creates intense harmonic tension — the tritone between root and diminished fifth is the most dissonant interval in Western music.
What is the symbol for the B Diminished?
B Diminished is written as Bdim or B°. The ° or "dim" symbol means both the third and fifth are minor/diminished. Do not confuse with Bdim7 or Bø (half-diminished), which include additional notes.
What are the inversions of B Diminished?
First inversion (B Diminished/D): D–F–B. Second inversion (B Diminished/F): F–B–D. Diminished triads are used in classical music as the vii° chord — the chord one semitone below the tonic, with strong resolution pull.
How is B Diminished used in music?
B Diminished most commonly functions as the vii° chord in a major key, creating strong resolution back to the tonic. It also works as a chromatic passing chord between two nearby chords, and in classical music as a brief point of dissonance. Jazz uses the full four-note dim7 more often than the triad.
What songs use diminished chords?
Michelle (Beatles) uses a diminished chord as a chromatic passing chord. Many classical pieces use vii°–I cadences. Jazz standards use dim7 chords as chromatic passing and approach chords. Diminished harmony also appears in flamenco and film music for dramatic tension.