Bdim7
B Diminished 7th — perfectly symmetrical stacked minor thirds — the ultimate passing chord, able to resolve almost anywhere.
The keys
B – D – F – A♭
What's inside Bdim7
| Note | Interval from root | Degree |
|---|---|---|
| B | Root | 1 |
| D | Minor 3rd | b3 |
| F | Diminished 5th | b5 |
| A♭ | Diminished 7th | bb7 |
Inversions
| Position | Keys (low → high) |
|---|---|
| Root position | B4 – D5 – F5 – A♭5 |
| 1st inversion | D5 – F5 – A♭5 – B5 |
| 2nd inversion | F5 – A♭5 – B5 – D6 |
| 3rd inversion | A♭5 – B5 – D6 – F6 |
A working voicing
Split the chord between two hands the way working players do — a solid shell low down, the colour tones up top:
| Hand | Keys |
|---|---|
| Left (shell) | B2 – A♭3 |
| Right (colour) | D5 – F5 |
Where Bdim7 lives
As the ii chord
Bdim7 → E7 → Amaj7
Minor-family sevenths live on the ii — this is the move they were born for.
Stepwise colour
B → Bdim7 → D♭m7
Used as a passing colour between neighbouring chords.
Put Bdim7 under your fingers
Hear every voicing, see the keys light up, and drill it in the interactive Chord & Voicing Lab.
Open the Chord & Voicing Lab →