The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
Bm7b5 is B, D, F and A — Bm7 with the fifth lowered a semitone.
It sounds hollow, and unmistakably going somewhere. Almost always the first chord of a minor ii–V–i, so it walks straight into an altered dominant.

| B | D | F | A |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭7 |
Pre-dominant — the ii of a minor key.
Also written Bø, Bø7, Bm7-5, Bm7(b5) or B half diminished. The same chord either way; which spelling you meet depends on who wrote the chart.
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
Bm7b5 has 10 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 13th — every inversion the chord has: B in the bass, D in the bass, F in the bass and A in the bass. The one to learn first is the F shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x2323x — no barre and down at the nut. None of the shapes for Bm7b5 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. 3 of the 8 need a barre. Together they cover the neck from the 2nd fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x2323x | 2nd fret | B, root position | D | all fretted |
| xx3435 | 3rd fret | F, 2nd inversion | A | all fretted |
| 7xx765 | 5th fret | B, root position | A | all fretted |
| 7x776x | 6th fret | B, root position | F | barred |
| 7-8-9-7-10-7 | 7th fret | B, root position | B | barred |
| x-x-9-10-10-10 | 9th fret | B, root position | D | barred |
| x-14-12-14-12-13 | 12th fret | B, root position | F | all fretted |
| x-14-15-14-15-x | 14th fret | B, root position | D | all fretted |
The same notes rebuilt from scratch give 8 shell, 15 drop 2 and 6 open string voicings, each on its own page.
Tensions. A shell of Bm7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (E) and the b13 (G).
Bm7b5 is the ii of A minor, which is where it is nearly always found: half-diminished, then an altered dominant, then the minor tonic.
In which keys. Every note of Bm7b5 belongs to C major (the vii°, the leading tone) and A minor (the ii°, the supertonic).
Every note of Bm7b5 is in B blues, B locrian, B altered and B half-whole diminished.
Change one note of Bm7b5 and you have Bdim (drop the flat seventh), Bdim7 (the flat seventh becomes a sixth), Bm7 (the flat fifth becomes a fifth), BmMaj7b5 (the flat seventh becomes a major seventh) or B7b5 (the minor third becomes a major third).
Bm7b5 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Bm7b5’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.