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B♭ diminished 7th chord on ukulele (B♭dim7)
Also called or written B♭dim7 or B♭°7
B♭ diminished 7th is built from B♭, D♭, F♭, A♭♭. The 3rd fret shape is a compact four-finger cluster that moves cleanly up and down the neck.
How it is built
Formula 1, ♭3, ♭5, ♭♭7
How do you play a B♭ diminished 7th chord on ukulele?
B♭ diminished 7th is played at the 3rd fret as 3 4 3 4: index finger on the G string at fret 3, ring finger on the C string at fret 4, middle finger on the E string at fret 3 and pinky finger on the A string at fret 4.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 3 | 1 | B♭ (1) |
| 3 (C) | 4 | 3 | F♭ (♭5) |
| 2 (E) | 3 | 2 | A♭♭ (6) |
| 1 (A) | 4 | 4 | D♭ (♭3) |
AdvancedThe pinky must reach fret 4 on the A string while the ring finger holds fret 4 on the C string, requiring a wide stretch.
B♭dim7/A♭♭ inversion
B♭ diminished 7th is played at the 6th fret as 6 7 6 7: index finger on the G string at fret 6, ring finger on the C string at fret 7, middle finger on the E string at fret 6 and pinky finger on the A string at fret 7.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 6 | 1 | D♭ (♭3) |
| 3 (C) | 7 | 3 | A♭♭ (6) |
| 2 (E) | 6 | 2 | B♭ (1) |
| 1 (A) | 7 | 4 | F♭ (♭5) |
9th fret
B♭ diminished 7th is played at the 9th fret as 9 10 9 10: index finger on the G string at fret 9, ring finger on the C string at fret 10, middle finger on the E string at fret 9 and pinky finger on the A string at fret 10.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | 9 | 1 | F♭ (♭5) |
| 3 (C) | 10 | 3 | B♭ (1) |
| 2 (E) | 9 | 2 | D♭ (♭3) |
| 1 (A) | 10 | 4 | A♭♭ (6) |
B♭dim7/D♭ inversion
B♭ diminished 7th is played in open position as 0 1 0 1: index finger on the C string at fret 1 and middle finger on the A string at fret 1. The G and E strings ring open.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (G) | open | — | A♭♭ (6) |
| 3 (C) | 1 | 1 | D♭ (♭3) |
| 2 (E) | open | — | F♭ (♭5) |
| 1 (A) | 1 | 2 | B♭ (1) |
Why it sounds like that
B♭ diminished 7th stacks minor thirds: 1, ♭3, ♭5, ♭♭7. The ♭♭7, A♭♭, sounds like G but is spelled as a diminished seventh to preserve the chord's structure. 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 mute the C string by lying flat.
- Pressing the pinky on the A string fret 4 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 2nd fret gives A diminished 7th.
- Sliding the shape up one fret to the 4th fret gives B diminished 7th.
Which voicing to use
The 3rd fret voicing puts B♭ in the bass, giving the most direct root-position sound. The B♭dim7/G inversion at the open position places A♭♭ 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 B♭dim7. The root is B♭, also written Bb. The chord is sometimes called B♭ diminished seventh. It is also spelled A♯ in enharmonic notation for the same sounding root.
Why does B♭ diminished 7th use A♭♭ instead of G?
The diminished seventh interval from B♭ is A♭♭, not G. Spelling it A♭♭ keeps the chord's formula as 1, ♭3, ♭5, ♭♭7. Using G would make the interval a major sixth.
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 3rd fret voicing uses four separate fingers. A barre would fret the G and E strings at fret 3, but you still need fingers for the C and A strings at fret 4.