Chord · B Diminished
Bdim Chord
Bdim is B, D and F — tense, unstable; resolves outward.
Bdim on every instrument
The same 3 notes, 6 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What Bdim is made of
Bdim (B diminished) is built from the notes B, D, F, with the interval pattern 1, b3, b5.
Stack 1, b3 and b5 on a root of B and you get B, D and F. 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 Bdim.
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. Every tone here lands on its own letter — no accidentals needed.
Keys that contain Bdim
All 3 notes sit inside the scale of 2 keys. The roman numeral marks the degree the chord is rooted on.
Major keys
Minor keys
Other chords on B
Same root, different colour.
The same diminished shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Bdim
- What notes are in the Bdim chord?
- Bdim is made of B, D and F — the 1, b3 and b5 degrees of a diminished chord built on B.
- What keys use the Bdim chord?
- Every note of Bdim belongs to 2 keys: C Major (vii°), A Minor (ii°). The roman numeral is the scale degree the chord is rooted on.
- How do you play Bdim on guitar and piano?
- This page shows Bdim 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.
Learn the theory behind it
Why Bdim behaves the way it does — the guides that explain the chord instead of just spelling it.