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B Diminished Chord

Bdim stacks two minor thirds: B to D, then D to F. Its lowered fifth creates a tritone above the root and gives the triad a strong need to move.

  • Notes: B-D-F
  • Symbol: Bdim
  • viidim in C major
  • Lowered fifth
Switch chordBdim

How to play a B diminished chord

Notes: B - D - F · symbol Bdim

  • Root position

    B - D - F
    C4C5
    Right hand 1-3-5 · Left 5-3-1

  • 1st inversion

    D - F - B
    C4C5
    Right hand 1-2-5 · Left 5-3-1

  • 2nd inversion

    F - B - D
    C4C5
    Right hand 1-3-5 · Left 5-2-1

Where does B diminished belong?

In C major, this diminished triad can act as a leading-tone chord that approaches the tonic.
Play the role cards to hear how its surrounding chords change the job it does; Diatonic Chords explains the basic numbered roles.

  • In C majorLeading-tone chord
    vii°

    B is the leading tone of C, so the chord leans hard toward it.

    CIFIVBdimvii°CI
  • In A minorThe ii° in minor
    ii°

    The minor-key version of ii-V-i, heading to Am.

    Bdimii°EVAmi
  • In C minorMinor-key pull
    vii°

    From harmonic minor: the same chord pulls just as hard toward Cm.

    CmiFmivBdimvii°Cmi

Progressions to try

  • CFBdimC

    Bdim is a leading-tone triad that resolves by step into the final major tonic.

  • BdimEAm

    In A minor, Bdim serves as ii diminished before the dominant and minor tonic.

  • CmFmBdimCm

    The leading-tone sound also works before a minor tonic; check the chord's spelling in this key.

Which shape should you use?

On guitar, start with the open x20401 grip. Let the open strings ring and keep any strings marked x silent.

On ukulele, start with 4212, played at the 1st fret. The 7575 grip moves the chord to another register.

On piano, play B-D-F. Move B up an octave to reach the first inversion, D-F-B; the notes remain the same while the lowest voice changes.

What are the inversions?

B is the root, D the minor third and F the diminished fifth, six semitones above the root.

  • Root position: B-D-F, with B lowest.
  • First inversion: D-F-B, written Bdim/D if D is lowest in the whole arrangement.
  • Second inversion: F-B-D, written Bdim/F if F is lowest in the whole arrangement.

A slash chord names the note in the bass, not merely the lowest note under one hand. Chord Inversions shows how to read that distinction.

How does Bdim differ from Bm?

Keep B and D, then raise the diminished fifth F to F sharp. That makes Bm. This page is about the three-note diminished triad, not a diminished seventh chord. Try that one-note change on piano, then use the comparer to hear it in the full chord. See Bm for the other chord's full spelling and roles.

  • Bdim

    B - D - F
    C4

    B diminished

  • Bm

    B - D - F#
    C4

    B minor

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