B♭ diminished seventh (B♭dim7) chord on piano

Looking for the B♭dim7 chord on piano? It is a diminished seventh chord (three stacked minor thirds), made of four notes: B♭ – D♭ – F♭ – A𝄫. The same chord with a different spelling: A♯ diminished seventh (A♯dim7).

Root position: B♭3 – D♭4 – F♭4 – A𝄫4

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What the B♭dim7 chord sounds like

A diminished seventh is three stacked minor thirds, so it is symmetrical: four different roots give the same notes. A dramatic, tense passing chord.

Notes of the B♭dim7 chord

Degree	Note	Interval from the root
1	B♭	root
3	D♭	minor third (3 semitones)
5	F♭	diminished fifth (6 semitones)
7	A𝄫	diminished seventh (9 semitones)

Root position and inversions

An inversion uses the same notes, with a different note at the bottom. When you change chords, choosing the nearest inversion keeps your hand almost still.

Root position

B♭3 – D♭4 – F♭4 – A𝄫4

1st inversion

D♭4 – F♭4 – A𝄫4 – B♭4

2nd inversion

F♭4 – A𝄫4 – B♭4 – D♭5

3rd inversion

A𝄫4 – B♭4 – D♭5 – F♭5

Similar chords and substitutes

If B♭dim7 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

F♯7 – an incomplete dominant: the diminished chord is the top of this seventh chord
B – where it leads (leading tone → root)

Same notes

C♯dim7 – the same notes with a different root
Edim7 – the same notes with a different root
Gdim7 – the same notes with a different root

Simpler versions

B♭dim – all 3 of its notes are in this chord

Frequently asked questions

What notes are in the B♭dim7 chord?

B♭, D♭, F♭, A𝄫. The root is B♭; the intervals of the other notes from the root: minor third, diminished fifth, diminished seventh.

How do I play the B♭dim7 chord on piano?

In root position, the right hand usually plays with fingers 1, 3 and 5 (thumb, middle finger, little finger); four-note chords with fingers 1, 2, 3 and 5. The left hand mirrors this: 5, 3, 1. In an inversion the top or bottom note moves to the other side, so your hand moves less when you change chords.

Why do some songbooks write H instead of B?

In German and Central European notation, H is the note B, and B is the note B♭. So a “B” chord in a German or Hungarian songbook is B♭ in English notation, and an “H” chord is B. Always check which notation your chord chart uses.