B♭ diminished chord on guitar (B♭dim)

Also called or written B♭dim or B♭°

B♭ diminished is built from B♭, D♭, and F♭. The open shape includes the high open E string, adding a bright edge to the otherwise dark chord.

B♭F♭B♭D♭F♭EADGBE
Positions on the neck1 of 5
Practice B♭ diminished chord

How it is built

B♭RootD♭Minor thirdF♭Diminished fifth

Formula 1, ♭3, ♭5

Inversions

How do you play a B♭ diminished chord on guitar?

B♭ diminished is played in open position as × 1 2 3 2 0: index finger on the A string at fret 1, middle finger on the D string at fret 2, pinky finger on the G string at fret 3 and ring finger on the B string at fret 2. The high e string rings open. The low E string stays muted.

Full note and interval breakdown
StringFretFingerNote
6 (E)muted
5 (A)11B♭ (1)
4 (D)22F♭ (♭5)
3 (G)34B♭ (1)
2 (B)23D♭ (♭3)
1 (e)openF♭ (♭5)

IntermediateThe open shape requires a four-fret stretch across the middle strings, making it intermediate despite the open high E.

6th fret

B♭ diminished is played at the 6th fret as 6 7 8 6 × ×: index finger on the low E string at fret 6, ring finger on the A string at fret 7, pinky finger on the D string at fret 8 and middle finger on the G string at fret 6. The B and high e strings stay muted.

Full note and interval breakdown
StringFretFingerNote
6 (E)61B♭ (1)
5 (A)73F♭ (♭5)
4 (D)84B♭ (1)
3 (G)62D♭ (♭3)
2 (B)muted
1 (e)muted

13th fret

B♭ diminished is played at the 13th fret as × 13 14 15 14 ×: index finger on the A string at fret 13, middle finger on the D string at fret 14, pinky finger on the G string at fret 15 and ring finger on the B string at fret 14. The low E and high e strings stay muted.

Full note and interval breakdown
StringFretFingerNote
6 (E)muted
5 (A)131B♭ (1)
4 (D)142F♭ (♭5)
3 (G)154B♭ (1)
2 (B)143D♭ (♭3)
1 (e)muted

B♭dim/D♭ inversion · fret 2

B♭ diminished is played at the 2nd fret as × 4 2 3 2 ×: pinky finger on the A string at fret 4, index finger on the D string at fret 2, ring finger on the G string at fret 3 and middle finger on the B string at fret 2. The low E and high e strings stay muted.

Full note and interval breakdown
StringFretFingerNote
6 (E)muted
5 (A)44D♭ (♭3)
4 (D)21F♭ (♭5)
3 (G)33B♭ (1)
2 (B)22D♭ (♭3)
1 (e)muted

B♭dim/D♭ inversion · fret 7

B♭ diminished is played at the 7th fret as 9 7 8 9 × ×: ring finger on the low E string at fret 9, index finger on the A string at fret 7, middle finger on the D string at fret 8 and pinky finger on the G string at fret 9. The B and high e strings stay muted.

Full note and interval breakdown
StringFretFingerNote
6 (E)93D♭ (♭3)
5 (A)71F♭ (♭5)
4 (D)82B♭ (1)
3 (G)94F♭ (♭5)
2 (B)muted
1 (e)muted

Why it sounds like that

B♭ diminished uses the formula 1, ♭3, ♭5, producing B♭, D♭, and F♭. The double-flatted fifth gives the chord its distinctive unstable sound. Contrast it with B♭ minor, which has a perfect fifth.

What goes wrong with B♭ diminished?

  • Letting the low E string sound, which adds an E that is not part of B♭ diminished.
  • Pressing the pinky on the G string too flat, causing the 3rd fret note to buzz.
  • Muting the high E string accidentally with the palm, losing the intended open note.

When to use it

B♭ diminished acts as the vii° chord in C♭ major, leading to C♭ major. It also works as a passing chord between B♭ minor and C♭ major. Use it in jazz or classical for a tense, dark color.

Changing to and from B♭ diminished

  • Slide the 6th fret shape down one fret to the 5th fret to get A diminished.
  • Move to B♭ minor by lifting the pinky from the G string's 3rd fret and playing the 2nd fret instead.

Which voicing to use

The open shape is the most accessible and keeps the root B♭ in the bass. The 6th fret and 13th fret shapes repeat the voicing higher. The B♭dim/C♯ inversions place D♭ in the bass, creating a more ambiguous sound.

Other B♭ chords

Common questions

How is B♭ diminished written?

B♭ diminished is written as B♭° or B♭dim. On a keyboard, use Bb for the root. It is also spelled A♯ in enharmonic notation for the same sounding root.

Why does the open shape include the high E string?

The high E string is open and is a chord tone of B♭ diminished. It adds a bright overtone to the otherwise dark harmony.

What is the difference between B♭ diminished and B♭ minor?

B♭ diminished has a flattened fifth (F♭), while B♭ minor has a perfect fifth (F). The diminished fifth creates a more dissonant, tense sound.