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New Released in April 2026

B Flat Diminished Chord on Piano (Bbdim)

To play Bbdim on the piano, press Bb, Db, Fb together. Start from Bbm and move the fifth down a semitone: that one key turns it into Bbdim. Here is where Bbdim comes from, where it resolves and how to play it with both hands.

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  • MIDI keyboard
  • Digital or acoustic piano
  • Guitar
  • Computer, phone or tablet
Bbdim Bb Db Fb

Bbdim compared with Bb, Bbm and the other triads

One key changes and the chord changes family.

ChordNotesThirdFifth
Bb Bb D Fmajor 3rdperfect 5th
Bbm Bb Db Fminor 3rdperfect 5th
Bbdim Bb Db Fbminor 3rddiminished 5th
Bbaug Bb D F#major 3rdaugmented 5th

What Bbdim does in music

  • Bbdim is the vii° chord of Cb major and the ii° chord of Ab minor.
  • It wants to move up a semitone: Bbdim → Cb / Cbm, the bottom note rising to the new root.
  • Add Ab and you get Bbm7b5 (half-diminished); add Abb instead and you get Bbdim7 (diminished 7th).

Bbm7b5 · Cb

The B flat diminished chord and its inversions

Move the lowest note up an octave to reach the next position.

Bbdim Bb Db Fb

Root position: Bb Db Fb

Bbdim Db Fb Bb

1st inversion: Db Fb Bb

Bbdim Fb Bb Db

2nd inversion: Fb Bb Db

  • Root position: starts on Bb, a black key; black keys: Bb, Db
  • 1st inversion: starts on Db, a black key; black keys: Db, Bb
  • 2nd inversion: starts on Fb, a white key; black keys: Bb, Db
ChordRunner showing a chord block while hands play the piano

Make Bbdim automatic

In ChordRunner Bbdim rides towards your runner between other chords: play it in time. MIDI keyboard or microphone, both work.

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All piano chords · Diminished chords explained

Common questions

What notes are in the B flat diminished chord?

Bbdim has three notes: Bb, Db, Fb. Root, minor 3rd and diminished 5th (formula 1 b3 b5).

What is the difference between Bbdim and Bbm?

One note. Bbm has F on top; Bbdim moves it to Fb. The new fifth is what gives Bbdim its tense sound.

Where does Bbdim go?

Bbdim is the vii° chord of Cb major and the ii° chord of Ab minor. It wants to move up a semitone: Bbdim → Cb / Cbm, the bottom note rising to the new root.

Can I practise Bbdim with a MIDI keyboard or microphone?

Yes. ChordRunner detects a USB MIDI keyboard automatically and also hears an acoustic piano through the microphone. Bbdim counts in any position, as long as Bb, Db, Fb sound together.

Your instrument is the controller.

ChordRunner is a browser game that teaches piano and guitar chords: a chord appears on screen, you play it on a real instrument, and your runner jumps. MIDI keyboard or microphone, both work.

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