Fdim7
F Diminished 7th — perfectly symmetrical stacked minor thirds — the ultimate passing chord, able to resolve almost anywhere.
The keys
F – A♭ – C♭ – D
What's inside Fdim7
| Note | Interval from root | Degree |
|---|---|---|
| F | Root | 1 |
| A♭ | Minor 3rd | b3 |
| C♭ | Diminished 5th | b5 |
| D (spelled E♭♭) | Diminished 7th | bb7 |
Inversions
| Position | Keys (low → high) |
|---|---|
| Root position | F4 – A♭4 – B4 – D5 |
| 1st inversion | A♭4 – B4 – D5 – F5 |
| 2nd inversion | B4 – D5 – F5 – A♭5 |
| 3rd inversion | D5 – F5 – A♭5 – B5 |
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) | F2 – D3 |
| Right (colour) | A♭4 – B4 |
Where Fdim7 lives
As the ii chord
Fdim7 → B♭7 → E♭maj7
Minor-family sevenths live on the ii — this is the move they were born for.
Stepwise colour
F → Fdim7 → Gm7
Used as a passing colour between neighbouring chords.
Put Fdim7 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 →