B diminished chord (Bdim)
The B diminished chord (Bdim) is a diminished triad: B, D and F, two minor thirds stacked on top of each other (root, minor third and diminished fifth).
It is the vii° in C major and the vii° in C minor; it sits inside G dominant seventh and tends to resolve to C major, a half step up.
Below: voicings, notes on the fretboard, ukulele, piano, inversions and progressions.
How to play B diminished on guitar
There are 2 guitar voicings.
Frets from the 6th string to the 1st: x = not played, 0 = open string.
- Voicing 1: x-2-3-4-3-x, with B in the bass (fingers x-1-2-4-3-x).
- Voicing 2: 7-8-9-7-x-x, barre at fret 7, with B in the bass (fingers 1-2-4-1-x-x).
Notes of the B diminished chord on the fretboard
B diminished has 3 notes: B, D and F. This is where they fall on each string, from the nut to the 12th fret (fret number in parentheses):
- String 6 (E): F (1) · B (7) · D (10)
- String 5 (A): B (2) · D (5) · F (8)
- String 4 (D): D (0) · F (3) · B (9) · D (12)
- String 3 (G): B (4) · D (7) · F (10)
- String 2 (B): B (0) · D (3) · F (6) · B (12)
- String 1 (E): F (1) · B (7) · D (10)
Formula and intervals of B diminished
Its formula is 1-♭3-♭5; in semitones from the root, 0-3-6.
- B: Root, the note that gives the chord its name
- D: Minor third (m3), 3 semitones above B
- F: Diminished fifth (d5), 6 semitones above B
B diminished on ukulele
- Ukulele (G C E A): 4-2-1-2; it sounds B, D, F and B.
B diminished on piano
- Keys: B4, D5 and F5.
Inversions of B diminished
Each inversion puts a different note in the bass.
- Root position: B, D and F, with B in the bass.
- First inversion (Bdim/D): D, F and B, with D in the bass.
- Second inversion (Bdim/F): F, B and D, with F in the bass.
Keys that use B diminished
B diminished appears in 3 major and minor keys.
| Key | Degree | Function |
|---|---|---|
| C major (no sharps or flats) | vii° | Leading tone |
| A minor (no sharps or flats) | ii° | Supertonic |
| C minor (harmonic minor, 3 flats) | vii° | Leading tone |
Progressions with B diminished
- Passing diminished chord in B♭ major (I–♯i°–ii–V): B♭ – Bdim – Cm – F
Frequently asked questions
What notes are in the B diminished chord?
B, D and F: root, minor third and diminished fifth. Its formula is 1-♭3-♭5.
Which keys use B diminished?
Mainly as the vii° in C major and the vii° in C minor. In total it appears in 3 major and minor keys.
Is B diminished the same as a diminished seventh chord?
No: B diminished is a triad with three notes (B, D and F). A diminished seventh chord adds a fourth note, another minor third on top.
Why does B diminished sound like G dominant seventh?
Because its three notes, B, D and F, are the third, fifth and seventh of G dominant seventh: it is that dominant seventh without its root. So it does the same job and resolves to C major.