Bbdim piano chord, Bb diminished notes and fingering.

The Bbdim piano chord is Bb diminished: the notes Bb, Db and Fb. It is two minor thirds stacked on top of each other. Bb up to Db is three semitones, and Db up to Fb is three more, so the fifth (Fb) is lowered to six semitones above the root. Chord charts write it as Bbdim or Bb°.

How to play Bbdim on piano

1. Find Bb on the keyboard. Bb is the third black key of the group of three, just before B. It is the same key as A#.
2. With your right hand, put finger 1 on Bb, finger 3 on Db and finger 5 on Fb. Finger 1 is the thumb.
3. Press all three keys together. In root position they run from Bb3 to Fb4, a reach of 6 semitones. Play chord sounds them together and Arpeggio sounds them one by one, from the bottom up.
4. Click Left hand to see the left hand. It plays Bb2 to Fb3, one octave lower: Bb with finger 5, Db with finger 3, Fb with finger 1.
5. The cards under the keyboard hold the three positions, with Bb, Db and Fb at the bottom in turn. Play and Arpeggio on a card play that position.
6. Open Note names. As written the keys read Bb, Db and Fb. Sharps shows A#, C# and E, and Flats shows Bb, Db and E. As written mixes sharps and flats on purpose, because each note takes its letter from its place in the chord.

How Bbdim is built

Counted from the root, the formula is 0, 3, 6. Stacked on each other the gaps are 3 + 3: two minor thirds. Compare it with Bb minor (Bb, Db and F): the first two notes are the same, and the fifth is lowered one semitone from F to Fb. A perfect fifth is seven semitones; this one is six, and six semitones is a tritone.

Worked example: the pitch of Bb3. On a piano tuned to A4 = 440 Hz, a note 11 semitones below A4 has the frequency 440 × 2^(-11/12), which is about 233.08 Hz. Db4 is 8 semitones below A4, so 440 × 2^(-8/12) gives about 277.18 Hz.

Bbdim and A#dim are the same chord on the keyboard: the same three keys sound for both. Written as A#dim it reads A#, C# and E.

What the keys look like under your hand

The white keys beside Bb are A on the left and B on the right, a semitone each way. Two of the three notes are black keys (Bb and Db) and one is a white key (Fb). Your thumb lands on Bb, a black key with A and B beside it. Keep the thumb relaxed and slightly curved, and let the wrist stay level instead of twisting to reach. Finger 3 presses Db, a black key between C and D. The middle fingers are the longest, so they reach black keys most easily.

Bbdim inversions and fingering

Bbdim has three positions. In root position Bb is at the bottom. In the first inversion, Db is at the bottom and the chord is written Bbdim/Db. In the second inversion, Fb is at the bottom and the chord is written Bbdim/Fb. The tightest reach, 6 semitones from the lowest key to the highest, is the root position. The widest, at 9, is the first inversion and second inversion.

The keys that hold Bbdim

Bbdim fits two of the major and natural minor keys that have a standard key signature, which means every note of it comes from that key's scale. The simplest is Cb major, with 7 flats, where it is chord vii°.

Progressions that use Bbdim, with the chord numbers and the chords in that key:

• Cb major: IV-vii°-iii-vi, which is Fb, Bbdim, Ebm, Abm, a run of falling fifths.
• Ab minor: ii°-v-i, which is Bbdim, Ebm, Abm, the minor ii-V-i, with the natural minor v.
• Cb major: vii°-I, which is Bbdim, Cb, the diminished chord leading up to the tonic.

Here is a worked example in Cb major. The chord before Bbdim in the first progression above is Fb (Fb, Ab and Cb). From Fb in root position, the closest way to reach Bbdim is its second inversion (Fb, Bb and Db, lowest note first): one note stays where it is, and the others move 4 semitones in total, counting each note against the note in the same place from the bottom.

Bbdim also sits inside Gb7 (Gb, Bb, Db and Fb): take the root off that dominant 7th and the notes left over are Bb, Db and Fb.

What Bbdim sounds like

A diminished triad sounds tense and unresolved. It rarely sits still: the usual move is up a semitone to the chord built on Cb. It is used as a passing chord between two others and as a spice inside a progression.

Bbdim is the vii° chord in Cb major and the ii° chord in Ab minor.

A common mistake with Bbdim

A common mistake is pressing F instead of Fb, one semitone higher than the fifth of Bbdim. That gives Bbm (Bb, Db and F), a plain minor chord. The top key of Bbdim is a semitone lower than you might expect, so check it against the chord of the same root.

Chords to learn next

Chords close to Bbdim: Bb minor (raises the fifth; shares Bb and Db); Gb7, listed as F#7 (the dominant 7th it sits inside; contains all its notes); Cb major, listed as B major (the chord it leads to; shares no note); Bbm7 (adds a minor seventh to the minor chord; shares Bb and Db).

Once Bbdim feels easy, play it and then Cb major to hear it resolve upward. For chords beyond these six types, and for guitar and ukulele shapes, use the chord finder. To play along with your computer keys, open the virtual piano. The piano chords page lists all 72 chords.