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B minor 7th flat 5th chord on bass (Bm7♭5)
Also called or written Bm7♭5, B or B Half Diminished Minor 7
B minor 7th flat 5th contains B, D, F and A. The 7th-fret shape spreads four fingers across two frets, demanding a wide left-hand stretch.
How it is built
Formula 1, ♭3, ♭5, ♭7
How do you play a B minor 7th flat 5th chord on bass?
B minor 7th flat 5th is played at the 7th fret as 7 8 7 7: index finger on the E string at fret 7, pinky finger on the A string at fret 8, middle finger on the D string at fret 7 and ring finger on the G string at fret 7.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 7 | 1 | B (1) |
| 3 (A) | 8 | 4 | F (♭5) |
| 2 (D) | 7 | 2 | A (♭7) |
| 1 (G) | 7 | 3 | D (♭3) |
AdvancedThe wide stretch between the index finger on the 4th string and the pinky on the 3rd string at the 7th fret is the hardest part.
Bm7♭5/F inversion · open position
B minor 7th flat 5th is played in open position as 1 2 0 2: index finger on the E string at fret 1, middle finger on the A string at fret 2 and ring finger on the G string at fret 2. The D string rings open.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 1 | 1 | F (♭5) |
| 3 (A) | 2 | 2 | B (1) |
| 2 (D) | open | — | D (♭3) |
| 1 (G) | 2 | 3 | A (♭7) |
Bm7♭5/F inversion · fret 12
B minor 7th flat 5th is played at the 12th fret as 13 14 12 14: middle finger on the E string at fret 13, ring finger on the A string at fret 14, index finger on the D string at fret 12 and pinky finger on the G string at fret 14.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 13 | 2 | F (♭5) |
| 3 (A) | 14 | 3 | B (1) |
| 2 (D) | 12 | 1 | D (♭3) |
| 1 (G) | 14 | 4 | A (♭7) |
Bm7♭5/A inversion
B minor 7th flat 5th is played at the 3rd fret as 5 5 3 4: ring finger on the E string at fret 5, pinky finger on the A string at fret 5, index finger on the D string at fret 3 and middle finger on the G string at fret 4.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 5 | 3 | A (♭7) |
| 3 (A) | 5 | 4 | D (♭3) |
| 2 (D) | 3 | 1 | F (♭5) |
| 1 (G) | 4 | 2 | B (1) |
Why it sounds like that
B minor 7th flat 5th is built from the formula 1, ♭3, ♭5, ♭7. The diminished 5th between B and F gives the chord its tense, unresolved quality. Raising the ♭5 to a perfect 5th produces B minor 7th, the closest stable contrast.
What goes wrong with B minor 7th flat 5th?
- Letting the pinky collapse and mute the 2nd string.
- Fretting the 1st string with the ring finger too far from the fret, causing a buzz.
- Allowing the index finger to touch the 3rd string and deaden the B.
When to use it
B minor 7th flat 5th functions as the ii chord in A natural minor and the vii chord in C major. Use it in minor-key jazz and blues lines where the half-diminished colour leads to a dominant. It pairs naturally with B minor and B 5th.
Changing to and from B minor 7th flat 5th
- Sliding the shape down two frets to the 5th fret gives A minor 7th flat 5th.
- Sliding the shape up one fret to the 8th fret gives C minor 7th flat 5th.
Which voicing to use
The 7th-fret root position keeps B in the bass for a grounded sound. The Bm7♭5/F inversion at the 1st fret places the diminished 5th in the bass, creating a darker, less stable feel. Choose the Bm7♭5/A inversion when the bass line needs to descend to A.
Other B chords
Common questions
How is B minor 7th flat 5th written?
B minor 7th flat 5th is written as Bm7♭5, and it is also called Half Diminished Minor 7.
What is the difference between B minor 7th flat 5th and B diminished?
B minor 7th flat 5th adds a minor 7th to the diminished triad. B diminished has only the root, ♭3 and ♭5.
Why does B minor 7th flat 5th sound unstable?
The tritone between B and F creates tension that wants to resolve. This instability makes the chord useful as a passing harmony.