What notes are in the Bbdim chord?

Bbdim is made of Bb, Db and Fb — the 1, b3 and b5 degrees of a diminished chord built on Bb.

What keys use the Bbdim chord?

Every note of Bbdim belongs to 4 keys: B Major (vii°), Cb Major (vii°), G# Minor (ii°), Ab Minor (ii°). The roman numeral is the scale degree the chord is rooted on.

How do you play Bbdim on guitar and piano?

This page shows Bbdim on guitar, piano, ukulele, bass, mandolin and banjo — 9 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.

Is Bbdim the same as A#dim?

Yes. Bbdim and A#dim are enharmonic — identical pitches written two different ways. Which spelling you use depends on the key you are in; Bbdim is the spelling this site treats as canonical.

Chord · Bb Diminished

B♭dim Chord

B♭dim is Bb, Db and Fb — tense, unstable; resolves outward.

Hear it

B♭dim on every instrument

The same 3 notes, 6 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.

What B♭dim is made of

Bb Diminished (Bb diminished) is built from the notes Bb, Db, Fb, with the interval pattern 1, b3, b5. A common diminished chord across many styles.

Stack 1, b3 and b5 on a root of B♭ and you get Bb, Db and Fb. That interval recipe is what makes the chord a diminished chord — move the same shape to another root and the character travels with it, which is why Cdim sounds like a transposed B♭dim.

Diminished: Tense, unstable; resolves outward.

Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with B♭ rather than its enharmonic equivalent.

Keys that contain B♭dim

All 3 notes sit inside the scale of 4 keys. The roman numeral marks the degree the chord is rooted on.

Major keys

Minor keys

Other chords on B♭

Same root, different colour.

B♭Bb Major B♭mBb Minor B♭augBb Augmented B♭sus2Bb Suspended 2nd B♭sus4Bb Suspended 4th B♭5Bb Power Chord B♭6Bb Major 6th B♭m6Bb Minor 6th

The same diminished shape, moved

The identical interval recipe, built on other roots.

CdimC Diminished DdimD Diminished EdimE Diminished FdimF Diminished GdimG Diminished AdimA Diminished BdimB Diminished C♯dimC# Diminished

Questions people ask about Bbdim

What notes are in the Bbdim chord?: Bbdim is made of Bb, Db and Fb — the 1, b3 and b5 degrees of a diminished chord built on Bb.
What keys use the Bbdim chord?: Every note of Bbdim belongs to 4 keys: B Major (vii°), Cb Major (vii°), G# Minor (ii°), Ab Minor (ii°). The roman numeral is the scale degree the chord is rooted on.
How do you play Bbdim on guitar and piano?: This page shows Bbdim on guitar, piano, ukulele, bass, mandolin and banjo — 9 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
Is Bbdim the same as A#dim?: Yes. Bbdim and A#dim are enharmonic — identical pitches written two different ways. Which spelling you use depends on the key you are in; Bbdim is the spelling this site treats as canonical.

Learn the theory behind it

Why B♭dim behaves the way it does — the guides that explain the chord instead of just spelling it.

Barre Chords — The Wall Every Guitarist ClimbsThis one asks for a barre. The article is the fix for the buzzing and the aching hand.7 min read Functional Harmony: Three Roles, One EngineDiminished chords are almost always doing a job. This explains which one.6 min read Cadences — The Four Ways a Phrase EndsWhere all that tension goes — how the chord resolves into the next one.4 min read