B diminished (Bdim) chord on piano

Diminished triad (two minor thirds) on B: the notes of the Bdim chord are B – D – F.

Root position: B3 – D4 – F4

What the Bdim chord sounds like

A diminished triad is two stacked minor thirds with a diminished fifth. It sounds tense and unsettled; in a major key it sits on degree vii and leads into the tonic.

Notes of the Bdim chord

Degree	Note	Interval from the root
1	B	root
3	D	minor third (3 semitones)
5	F	diminished fifth (6 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

B3 – D4 – F4

1st inversion

D4 – F4 – B4

2nd inversion

F4 – B4 – D5

Which keys is it in?

The Bdim chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

C major: vii°
C minor: vii°
A minor: ii°

Similar chords and substitutes

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

Substitutes (by function)

G7 – an incomplete dominant: the diminished chord is the top of this seventh chord
C – where it leads (leading tone → root)

Richer versions

Bdim7 – the same chord plus 1 colour note
Bm7b5 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the Bdim chord?

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

How do I play the Bdim 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.