The B Half Diminished chord is a four-note chord made up of B, D, F, and A. It is built from a root, minor third, diminished fifth, and minor seventh.
Construction
B Half Diminished = Root + Minor 3rd + Diminished 5th + Minor 7th = B · D · F · A
| Note | Interval | Degree |
|---|---|---|
| B | Root | 1 |
| D | Minor 3rd | ♭3 |
| F | Diminished 5th | ♭5 |
| A | Minor 7th | ♭7 |
B Half Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | B – D – F – A |
| 1st Inversion | D – F – A – B |
| 2nd Inversion | F – A – B – D |
| 3rd Inversion | A – B – D – F |
Key Signature
A Half Diminished chord is built from symmetrical or ambiguous intervals, so it doesn’t belong to a single key and has no key signature of its own.
How B Half Diminished functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where B Half Diminished sits diatonically across the common keys:
- In C major, B Half Diminished is the vii° chord — the dominant.
- In A minor, B Half Diminished is the ii° chord — a predominant.
Same Notes, Other Names
The notes B – D – F – A aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:
B Half Diminished — Frequently Asked Questions
What is the B Half Diminished chord on piano?
The B Half Diminished chord contains the notes B – D – F – A. On piano, play these notes together to sound the chord.
What notes are in the B Half Diminished chord?
Bm7b5 contains: B, D, F, A. All white keys. Diminished triad with minor seventh.
How does Bm7b5 differ from Bdim7?
Minor seventh (A) vs diminished seventh (Ab).
How is Bm7b5 used?
ii chord in A minor (Bm7b5–E7–Am). Also the vii chord in C Major. Extremely common.
What songs use Half Diminished?
Bm7b5 is the vii in C Major — one of the most common half-diminished chords. Jazz standards.
How does Bm7b5 differ from Bm7?
Flatted fifth (F vs F#).
Is Bm7b5 the same as Dm6?
Same notes (B, D, F, A = D, F, A, B).