B♭ half-diminished (B♭m7b5) chord on mandolin

The B♭ half-diminished chord (B♭m7b5) is a half-diminished seventh chord (a diminished triad plus a minor seventh), made of four notes: B♭ – D♭ – F♭ – A♭. The same chord with a different spelling: A♯ half-diminished (A♯m7b5).

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Basic shapemedium

Position 6medium

Position 8medium

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What the B♭m7b5 chord sounds like

The half-diminished (m7b5) chord is a diminished triad with a minor seventh. In a minor key it sits on degree ii – the first chord of the minor ii–V–i.

Notes of the B♭m7b5 chord

Degree	Note	Interval from the root
1	B♭	root
3	D♭	minor third (3 semitones)
5	F♭	diminished fifth (6 semitones)
7	A♭	minor seventh (10 semitones)

How to play it – with fingering

Basic shape

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

Position 6

String 1 (E): fret 6, ring finger (B♭5)
String 2 (A): fret 7, little finger (F♭5)
String 3 (D): fret 6, middle finger (A♭4)
String 4 (G): fret 6, index finger (D♭4)

Position 8

String 1 (E): fret 9, ring finger (D♭6)
String 2 (A): fret 11, little finger (A♭5)
String 3 (D): fret 8, index finger (B♭4)
String 4 (G): fret 9, middle finger (F♭4)

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.

Similar chords and substitutes

If B♭m7b5 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

F♯9 – a rootless dominant ninth: the same notes over a root a major third lower
E♭7 – the next chord in a minor ii–V–i (V)

Same notes

C♯m6 – 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♭m7b5 chord?

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

What is the easiest way to play B♭m7b5 on mandolin?

The easiest shape above is “Basic shape”. 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.