Chord and FretBdim7 — diminished seventh
Notes in Bdim7: B – D – F – AbFormula: 1 – b3 – b5 – bb7In the formula, the numbers count steps of the major scale starting from the note that names the chord; "b" lowers a half step, "#" raises one — and a slash names the bass note.
The diminished seventh stacks three minor thirds (1–b3–b5–bb7), forming a symmetrical and highly tense chord. It can stand in for a dominant with the root omitted.
The same chord on all four instruments
Where to use it: Between two neighbouring chords it acts as a half-step stair: in C → C#° → DmDmDmDm it is the little step that pushes the music forward. In practice it is a passing chord — you barely notice it, but you feel the motion.
This is just one shape of Bdim7. In Chord and Fret, you hear every shape strummed string by string, in each instrument's own voice; compare positions with their difficulty marked; and change the tuning — the shape rewrites itself. Start free. Unlock everything with Pro. Plays offline.
See the whole neck in Chord and Fret →Part of the Sevenths family.