1b3b5bb7
Fig. 1 · Bdim7 on the keyboard

piano chord

Bdim7

B1D♭3F♭5A♭♭♭7

Three minor thirds stacked. The seventh is doubly diminished, which is why it is written with a double flat.

on guitaron ukulelethe scale

What is true of it

Bdim7 is B, D, F and A♭ — 1, b3, b5 and bb7 counted from B.

B in other shapes

B7dominant seventhBmaj7major seventhBm7minor seventhBmajorBmminorBdimdiminished

Cdim7C♯dim7D♭dim7Ddim7D♯dim7E♭dim7Edim7Fdim7all 374