B diminished seventh (Bdim7) chord on mandolin

The B diminished seventh chord (Bdim7) is a diminished seventh chord (three stacked minor thirds), made of four notes: B – D – F – A♭.

Dots show:

Basic shapeeasy

Position 3medium

Position 6medium

Position 9medium

Tap a string on a diagram to hear just that string. The sound is generated in your browser with a physical string model.

Chord finder Transposer Tuner

What the Bdim7 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 Bdim7 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)

How to play it – with fingering

Basic shape

String 1 (E): fret 1, middle finger (F5)
String 2 (A): fret 2, ring finger (B4)
String 3 (D): open (D4)
String 4 (G): fret 1, index finger (A♭3)

Position 3

String 1 (E): fret 4, ring finger (A♭5)
String 2 (A): fret 5, little finger (D5)
String 3 (D): fret 3, index finger (F4)
String 4 (G): fret 4, middle finger (B3)

Position 6

String 1 (E): fret 7, ring finger (B5)
String 2 (A): fret 8, little finger (F5)
String 3 (D): fret 6, index finger (A♭4)
String 4 (G): fret 7, middle finger (D4)

Tuning: G D A E, like a violin; every note is a pair of strings that you fret together. In the diagram, × means the string is not played, and a circle means an open string.

Which keys is it in?

The Bdim7 chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

C minor: vii°7

Similar chords and substitutes

If Bdim7 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)

Same notes

Ddim7 – the same notes with a different root
Fdim7 – the same notes with a different root
A♭dim7 – the same notes with a different root

Simpler versions

Bdim – all 3 of its notes are in this chord

Frequently asked questions

What notes are in the Bdim7 chord?

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

What is the easiest way to play Bdim7 on mandolin?

The easiest shape above is “Basic shape”, rated easy. We show 4 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.