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B diminished 7th chord on ukulele (Bdim7)
Also called or written Bdim7 or B°7
B diminished 7th is built from B, D, F, A♭. The 4th fret shape sits high enough to require clean finger placement on every string.
How it is built
Formula 1, ♭3, ♭5, ♭♭7
- Root positionB–D–F–A♭Bdim710-11-10-11
- First inversionD–F–A♭–BBdim7/D1-2-1-2
- Second inversionF–A♭–B–DBdim7/F4-5-4-5
- Third inversionA♭–B–D–FBdim7/A♭7-8-7-8
How do you play a B diminished 7th chord on ukulele?
B diminished 7th is played at the 4th fret as 4 5 4 5: index finger on the G string at fret 4, ring finger on the C string at fret 5, middle finger on the E string at fret 4 and pinky finger on the A string at fret 5.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 4 | 1 | B (1) |
| 3 (C) | 5 | 3 | F (♭5) |
| 2 (E) | 4 | 2 | A♭ (6) |
| 1 (A) | 5 | 4 | D (♭3) |
AdvancedThe pinky must reach fret 5 on the A string while the ring finger holds fret 5 on the C string, creating a wide stretch.
Bdim7/A♭ inversion
B diminished 7th is played at the 7th fret as 7 8 7 8: index finger on the G string at fret 7, ring finger on the C string at fret 8, middle finger on the E string at fret 7 and pinky finger on the A string at fret 8.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 7 | 1 | D (♭3) |
| 3 (C) | 8 | 3 | A♭ (6) |
| 2 (E) | 7 | 2 | B (1) |
| 1 (A) | 8 | 4 | F (♭5) |
10th fret
B diminished 7th is played at the 10th fret as 10 11 10 11: index finger on the G string at fret 10, ring finger on the C string at fret 11, middle finger on the E string at fret 10 and pinky finger on the A string at fret 11.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 10 | 1 | F (♭5) |
| 3 (C) | 11 | 3 | B (1) |
| 2 (E) | 10 | 2 | D (♭3) |
| 1 (A) | 11 | 4 | A♭ (6) |
Bdim7/D inversion
B diminished 7th is played at the 1st fret as 1 2 1 2: index finger on the G string at fret 1, ring finger on the C string at fret 2, middle finger on the E string at fret 1 and pinky finger on the A string at fret 2.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 1 | 1 | A♭ (6) |
| 3 (C) | 2 | 3 | D (♭3) |
| 2 (E) | 1 | 2 | F (♭5) |
| 1 (A) | 2 | 4 | B (1) |
Why it sounds like that
B diminished 7th stacks minor thirds: 1, ♭3, ♭5, ♭♭7. Its altered interval creates tension while the supplied root and remaining tones stay fixed. Compare it with B minor 7th flat 5th, which has a minor seventh instead.
What goes wrong with B diminished 7th?
- Letting the index finger collapse and mute the C string.
- Pressing the pinky on the A string fret 5 without enough arch, deadening the E string.
- Strumming before all four fingers are firmly placed.
When to use it
B diminished 7th works as a passing chord between B minor 7th flat 5th and C♯ minor. Its tense, symmetrical sound suits jazz turnarounds and dramatic pauses in ballads.
Changing to and from B diminished 7th
- Sliding the shape down one fret to the 3rd fret gives B♭ diminished 7th.
- Sliding the shape up one fret to the 5th fret gives C diminished 7th.
Which voicing to use
The 4th fret voicing puts B in the bass, giving the most direct root-position sound. The Bdim7/D inversion at the 7th fret places D in the bass, which softens the chord's attack and works well when moving to a C♯ chord.
Other B chords
Common questions
How is B diminished 7th written?
B diminished 7th is written B°7 or Bdim7. The root is B. The chord is sometimes called B diminished seventh.
How does this supplied chord create its distinctive sound?
Its verified note order explains the sound without relying on outside harmony. Spelling it A♭ keeps the chord's formula as 1, ♭3, ♭5, ♭♭7. Check the exact supplied position before changing register or fingering.
How does B diminished 7th differ from B minor 7th flat 5th?
B minor 7th flat 5th has a minor seventh, A, while B diminished 7th has a diminished seventh, A♭. That one-semitone difference makes the diminished chord sound more tense and symmetrical.
Can I play B diminished 7th with a barre?
No, the 4th fret voicing uses four separate fingers. A barre would fret the G and E strings at fret 4, but you still need fingers for the C and A strings at fret 5.