Sevenths
B diminished 7th chord
Symmetrical and very tense — every note is a minor 3rd apart.
Bdim7 is the vii°7 chord in C minor.
- Notes
- BDFA♭
- Formula
- 1♭3♭5𝄫7
- Built from
- root · minor 3rd · diminished 5th · diminished 7th
How to play Bdim7
About the B diminished 7th chord
Playing it
On guitar, Bdim7 has an open-position shape, x20101, using three fingers alongside the open strings. Don’t strum the low E string.
On piano, Bdim7 has one black key (A♭) and three white keys.
On ukulele the usual Bdim7 shape is 1212, using four fingers.
Related chords
Take away the root and the other three notes form Ddim (D F A♭) — so you can think of Bdim7 as Ddim with B added underneath.
Bdim7 is symmetrical — its notes are evenly spaced — so Ddim7, Fdim7 and A♭dim7 contain exactly the same notes. There are only three different-sounding diminished 7th chords in all.
Move a single note and Bdim7 becomes a different chord: drop the A♭ for Bdim, raise F to F♯ for Bm6 and raise A♭ to A for Bm7♭5.
