Bdim chord on piano
Bdim (B diminished) is a diminished chord built on B. It has 3 notes, B, D and F, and its formula is 1 ♭3 ♭5.
Notes and intervals of Bdim
From the root upwards, Bdim contains root (B), minor 3rd (D) and diminished 5th (F). Those intervals give the chord its colour: the formula 1 ♭3 ♭5 works the same way in every key, so once you know it for B you can build the chord on any note.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | B |
| ♭3 | minor 3rd | D |
| ♭5 | diminished 5th | F |
How to play Bdim on piano
Find B and play B, D and F together. With the right hand, a common fingering is 1-3-5. With the left hand, reverse it (5-3-1). Keep your wrist level and let the fingers curve, so all 3 keys go down at the same time.
Inversions of Bdim
An inversion keeps the same notes but puts another one in the bass. Bdim has 2 inversions besides root position: 1st inversion (D F B) and 2nd inversion (F B D). Inversions let you move between chords with tiny hand movements, which is how pianists make progressions sound smooth.
Which keys use Bdim?
You find Bdim as a diatonic chord in C major (vii°). The most common case is C major, where it plays the role of vii°.
Scales to play over Bdim
To improvise over Bdim, start with B blues scale. All of these scales contain every note of the chord: B blues scale and B Locrian mode. Aim for the chord notes on strong beats and use the other notes to move between them.
About diminished chords
Two stacked minor thirds: 1 ♭3 ♭5. The diminished fifth (a tritone) makes the diminished chord the most unstable triad: tense, dark and restless. It rarely stands alone and pulls towards the chord a semitone above its root. For example Bdim: B D F. Add a diminished seventh and you get the symmetrical diminished seventh chord.
In a major key it sits on vii° (for example Bdim in C major), acting as a lighter V7 that resolves to I. In a minor key it sits on ii°. Passing diminished chords connect neighbouring chords chromatically, for example I ♯i° ii (C C♯dim Dm). Classical music, jazz, ragtime and film scores use it to build suspense.
Root position 1 ♭3 ♭5 sits under fingers 1 3 5. Because it is so unstable, voice-lead it: keep each note within a semitone or a tone of where the next chord's notes are. In classical harmony vii° is often played in first inversion (third in the bass), with that bass note doubled rather than the root.
dim (three notes) and dim7 (four notes, with a diminished seventh) are not the same, though 'dim' on a jazz chart often means dim7. And dim is not m7♭5: the half-diminished chord adds a minor seventh (for example Bm7♭5: B D F A) and sounds much softer. Symbols: ° means diminished, ø means half-diminished.
Frequently asked questions
What notes are in the Bdim chord?
Bdim (B diminished) contains B, D and F. In intervals: root (B), minor 3rd (D) and diminished 5th (F).
How do you play Bdim on piano?
Play B, D and F together with the right-hand fingering 1-3-5. You can also play it in 2 inversions, shown on this page.
What scale goes with Bdim?
B blues scale fits Bdim best. Other scales that contain all its notes: B Locrian mode.
What key is Bdim in?
Bdim belongs to C major (vii°). In C major it is the vii° chord.
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