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Bb Diminished Chord

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

  • Notes: B flat-D flat-F flat
  • Symbol: Bbdim
  • viidim in B major
  • Lowered fifth
Switch chordBbdim

How to play a Bb diminished chord

Notes: Bb - Db - Fb · symbol Bbdim

  • Root position

    Bb - Db - Fb
    C4C5
    Right hand 1-3-5 · Left 5-3-1

  • 1st inversion

    Db - Fb - Bb
    C4C5
    Right hand 1-2-5 · Left 5-3-1

  • 2nd inversion

    Fb - Bb - Db
    C4C5
    Right hand 1-3-5 · Left 5-2-1

Where does Bb diminished belong?

In B 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 B majorLeading-tone chord
    vii°

    B flat is the leading tone of B, so the chord leans hard toward it. In this key the chord is spelled A#dim.

    BIEIVA#dimvii°BI
  • In Ab minorThe ii° in minor
    ii°

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

    Bbdimii°EbVAbmi
  • In B minorMinor-key pull
    vii°

    From harmonic minor: the same chord pulls just as hard toward Bm. In this key the chord is spelled A#dim.

    BmiEmivA#dimvii°Bmi

Progressions to try

  • BEA#dimB

    Bbdim is a leading-tone triad that resolves by step into the final major tonic. Here the same sounding chord is written A#dim rather than Bbdim.

  • BbdimEbAbm

    In Ab minor, Bbdim serves as ii diminished before the dominant and minor tonic.

  • BmEmA#dimBm

    The leading-tone sound also works before a minor tonic; check the chord's spelling in this key. Here the same sounding chord is written A#dim rather than Bbdim.

Which shape should you use?

On guitar, start with the open x12320 grip. Let the open strings ring and keep any strings marked x silent.

On ukulele, the open shape 3101 is the easiest place to start. The 6464 grip moves the chord to another register.

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

What are the inversions?

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

  • Root position: B flat-D flat-F flat, with B flat lowest.
  • First inversion: D flat-F flat-B flat, written Bbdim/Db if D flat is lowest in the whole arrangement.
  • Second inversion: F flat-B flat-D flat, written Bbdim/Fb if F flat 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 Bbdim differ from Bbm?

Keep B flat and D flat, then raise the diminished fifth F flat to F. That makes Bbm. 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 Bbm for the other chord's full spelling and roles.

  • Bbdim

    Bb - Db - Fb
    C4

    Bb diminished

  • Bbm

    Bb - Db - F
    C4

    Bb minor

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