B diminished (Bdim) chord on banjo

The B diminished chord (Bdim) is a diminished triad (two minor thirds), made of three notes: B – D – F.

Dots show:

Basic shapeeasy

Position 10medium

Position 6medium

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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)

How to play it – with fingering

Basic shape

String 1 (D): fret 3, index finger (F4)
String 2 (B): open (B3)
String 3 (G): fret 4, middle finger (B3)
String 4 (D): open (D3)

Position 10

String 1 (D): fret 12, little finger (D5)
String 2 (B): fret 12, little finger (B4)
String 3 (G): fret 10, index finger (F4)
String 4 (D): fret 12, ring finger (D4)

Position 6

String 1 (D): open (D4)
String 2 (B): fret 6, index finger (F4)
String 3 (G): fret 7, middle finger (D4)
String 4 (D): fret 9, little finger (B3)

Five-string banjo in open G tuning (g D G B D). The diagram shows the four long strings; the short 5th string (g) rings open – avoid it when G is not in the chord. In the diagram, × means the string is not played, and a circle means an open string.

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.

What is the easiest way to play Bdim on banjo?

The easiest shape above is “Basic shape”, rated easy. We show 3 shapes, from open and easy versions to movable barre shapes higher up the neck.

How do I read the chord diagram?

Strings run from the lowest (left) to the highest (right) – tick “Left-handed” to mirror it. Rows are frets; a number at the side shows the starting fret. Dots are fingers (1 index, 2 middle, 3 ring, 4 little), a long bar is a barre, × means don't play that string and ○ means play it open.

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.