Root position
B – D – FThe root B is the lowest note. This is the shape most people learn first.
3 notes · 1 · ♭3 · ♭5
B Diminished Piano Chord (Bdim)
Bdim is built from B, D and F — the formula 1 · ♭3 · ♭5, or 3 and 6 semitones above B. The shape uses white keys only, and you can hear it, invert it and compare it below.
Chord
B Diminished
Notes
B · D · FFormula
1 · ♭3 · ♭5Right hand
1 · 3 · 5C
D
E
F
G
A
B
C
C#
D#
F#
G#
A#
Choose a chord, then play it. Finger numbers run from thumb (1) to little finger (5).
The finder above already holds Bdim. Press P or the Play chord button to hear B, D, F sounded together, then change the root or the chord type to compare it with something else.
Chord tones
The notes in Bdim
A diminished triad is two minor thirds stacked on top of each other, which squeezes the fifth a semitone flat. The result is tense and unresolved. It appears on the seventh degree of a major scale and on the second degree of a minor key, and it usually leads straight back to a more stable chord.
| Note | Interval | Degree | Semitones | Right hand |
|---|---|---|---|---|
| Bwhite key | Root | 1 | 0 | 1 · thumb |
| Dwhite key | Minor third | ♭3 | 3 | 3 · middle finger |
| Fwhite key | Diminished fifth | ♭5 | 6 | 5 · little finger |
Step by step
How to play Bdim on piano
- Find B: it is the white key immediately right of a group of three black keys.
- Build upwards from B using 3 and 6 semitones to reach D and F.
- With the right hand, place finger 1 on B, finger 3 on D and finger 5 on F. Keep the wrist level and the knuckles rounded.
- Every note here is a white key, so you can sit your hand slightly further out from the fallboard.
- Play the notes together, then one at a time from the bottom up, and listen to how Bdim settles.
- Try first inversion as well: D – F – B. Inversions let you change chords without jumping around the keyboard.
Inversions
Bdim in 3 positions
An inversion keeps the same 3 notes and simply moves the lowest one up an octave. Learning them means you can change chords with small hand movements instead of jumping to a new part of the keyboard.
First inversion
D – F – BD is the lowest note, so the minor third sits in the bass and the notes below it move up an octave.
Second inversion
F – B – DF is the lowest note, so the diminished fifth sits in the bass and the notes below it move up an octave.
In context
Which keys contain Bdim
In C major the chord functions as vii°. Altogether it is produced by the scales of 3 keys, so learning it once pays off in several places.
- C majorvii°
- C harmonic minorvii°
- A minorii°
Chord tones are spelled by the degree they occupy, so the third of a minor chord is written as a flat rather than a sharp even though it is the same key on the piano. A double sharp such as F## means the key one whole tone above F.
Compare
Bdim against B minor
Bdim and B minor share B and D. Moving the perfect fifth F# down 1 semitone to the diminished fifth F turns B minor into Bdim.
Practise the pair together: hold the shared notes B, D still and move only the one finger. Hearing that single change is the quickest way to recognise the two chords by ear.
Open B minor →Good questions
Bdim questions
What notes are in the Bdim chord?
Bdim contains B, D and F. Counted from the root, that is the formula 1 · ♭3 · ♭5, or 3 and 6 semitones above B.
What is the right-hand fingering for Bdim?
A comfortable beginner fingering is 1 (thumb) on B, 3 (middle finger) on D and 5 (little finger) on F. Finger numbers run from the thumb (1) to the little finger (5), and they change once you start using inversions.
How is Bdim different from B minor?
Bdim and B minor share B and D. Moving the perfect fifth F# down 1 semitone to the diminished fifth F turns B minor into Bdim.
Which keys use the Bdim chord?
It occurs naturally in C major (vii°), C harmonic minor (vii°) and A minor (ii°). The roman numeral shows which degree of the key the chord is built on.
What are the inversions of Bdim?
root position is B – D – F, first inversion is D – F – B and second inversion is F – B – D. Every inversion holds the same notes; only the lowest one changes.