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The Bdim chord

Start with the recipe. The notes are B - D - F, a diminished triad, otherwise known as the Bdim. The chord feels unstable, tense, transitional, which is why writers chasing a moment of unease keep landing on it. The vii chord in C major, and a turnaround colour in jazz standards. You will find it inside jazz turnarounds and ragtime piano. The rest of this page lays out the common voicings, the interval theory, the progressions where the chord fits, and the records that lean on it for structural work.

Hear the Bdim in the chord builder →
Scale degrees Note names

Voicings for Bdim

Common ways to grip the Bdim on guitar and piano. Guitar diagrams read low E to high E left-to-right; an × means muted, an open circle above the nut means an open string. Filled dots are fretted notes.

Guitar , full chord shapes

CAGED-derived voicings for Bdim across the neck. Pick the shape closest to where your hand already sits.

Guitar: A-string dim at fr.2
Notes: B - D - F (chord tones)
Guitar: D-string dim at fr.9
Notes: B - D - F (chord tones)
Guitar: top-4 voicing
Notes: B - D - F (chord tones)

Guitar , triad shapes

Three-note triad shapes on each string set, shown moving up the neck. Light textures for arpeggios, pop layering and chord-melody work.

Triad: top strings (G-B-e) · fr.1
Notes: top-string triad, fr.1
Triad: top strings (G-B-e) · fr.6
Notes: top-string triad, fr.6
Triad: top strings (G-B-e) · fr.10
Notes: top-string triad, fr.10
Triad: middle strings (D-G-B) · fr.3
Notes: middle-string triad, fr.3
Triad: middle strings (D-G-B) · fr.6
Notes: middle-string triad, fr.6
Triad: middle strings (D-G-B) · fr.10
Notes: middle-string triad, fr.10
Triad: bass strings (A-D-G) · fr.3
Notes: bass-side triad, fr.3
Triad: bass strings (A-D-G) · fr.7
Notes: bass-side triad, fr.7
Triad: bass strings (A-D-G) · fr.10
Notes: bass-side triad, fr.10

Piano voicings

Root position and inversions. The bass note matters: each inversion changes how the chord sits under a melody.

Piano: root position
Notes: B - D - F. Root B at the bottom. The classic stacked-thirds spelling of a diminished triad.
Piano: first inversion
Notes: D - F - B. D at the bottom. Common in chord-melody, walking bass lines and gentler voicings.
Piano: second inversion
Notes: F - B - D. F at the bottom. A floating, suspended feel often used in hymns and ballads.

The theory behind Bdim

The Bdim chord (B - D - F) is a diminished triad. Its intervals are root, minor third, diminished fifth. Functionally it lives at home in C major as the Leading tone (vii°), but you'll also find it in A minor as the Supertonic (ii°). The chord tends to resolve up a half-step or down to the I, which is why it shows up in ragtime and jazz.

Progressions that use Bdim

Short progressions that put the Bdim to work. Each one is shown in a different key so you can pick the one that suits your singer.

iivV key of A minor
Bdim (as passing colour)

This chord appears as a borrowed or passing chord in many minor-key progressions.

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Songs that feature Bdim

Real records where this chord does structural work. No lyrics quoted, just the title and artist so you can pull up a copy and hear it in context.

Related chords

Chords a step away from the Bdim in the songwriting circle, the natural neighbours when you want a substitution.

Keys where Bdim lives

The keys where this chord turns up diatonically. Open any key page for the full set of progressions that lean on it.

Related references

Other ways to put the Bdim to work across the reference library.

More songwriting tools

Got the chord but still wrestling with the lyric? Find the right rhyme in RhymeForge, or break a writer's block with the unexpected word-pair generator in CollisionLab. Need to map a full progression? The chord builder on the home page is where the Bdim fits into context. All free, no signup.

About the chord builder

The Undercover Zest chord progression builder is a free interactive tool that maps every diatonic and borrowed chord in every key. Click a Roman numeral to hear it, drag chords into a progression, then audition voicings, inversions and tensions until the song clicks.

This page is a static reference for the Bdim. For interactive playback, voice-leading hints and substitution suggestions, open the chord builder above.