What notes are in a B diminished 7 chord?

B°7 contains four notes: B (root), D (minor third), F (diminished fifth), and A♭ (diminished seventh).

How does B°7 resolve?

In C minor: B rises to C (the leading-tone resolution), D holds or rises to E♭, F holds, A♭ falls to G. Every voice moves to a chord tone of C minor.

Is B°7 the same as D°7?

Enharmonically yes — both contain the same four pitches in different inversions. B°7, D°7, F°7, and A♭°7 are inversions of each other.

Where does B°7 appear in famous music?

Beethoven's "Pathétique" Sonata Op. 13 (which opens with this exact chord), Mozart's C minor sonata K. 457, and Schubert's C-minor literature all use B°7 as the primary cadential preparation.

B diminished 7 chord — notes, intervals, and practice

B°7 — B, D, F, A♭ — is the vii°7 of C minor and one of the most-played dim7 chords in classical literature. The chord is enharmonically equivalent to D°7, F°7, and A♭°7 — all share the same four pitches. The single flat (A♭) on top of three naturals is its visual signature.

Intervals

The B diminished 7 chord stacks two thirds on the root. Each interval and its size in semitones:

B→Dminor 3rd3 semitones
D→Fminor 3rd3 semitones
F→Abdiminished 7th9 semitones

On the keyboard

Each note of the B diminished 7 chord highlighted on a piano. Pitch class is what matters — any octave works.

On the guitar

One voicing of the B diminished 7 chord on a six-string guitar fretboard.

Common mistakes

B°7 has B-D-F-A♭ — three naturals plus the flat seventh. The most common error is reading A♭ as A natural, which produces Bm7♭5 (half-diminished). The diminished 7th distinction is the lowered seventh, which gives the chord its full symmetry and its strong cadential pull.

In context

B°7 → C minor is the textbook leading-tone cadence in C minor. Beethoven's "Pathétique" Sonata Op. 13 opens with this exact dim7 → tonic-minor resolution. The chord also appears in C major as a borrowed harmony from the parallel C minor — a colour Beethoven and Schubert used constantly.

Drill it

The B diminished 7 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.

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Frequently asked

What notes are in a B diminished 7 chord?: B°7 contains four notes: B (root), D (minor third), F (diminished fifth), and A♭ (diminished seventh).
How does B°7 resolve?: In C minor: B rises to C (the leading-tone resolution), D holds or rises to E♭, F holds, A♭ falls to G. Every voice moves to a chord tone of C minor.
Is B°7 the same as D°7?: Enharmonically yes — both contain the same four pitches in different inversions. B°7, D°7, F°7, and A♭°7 are inversions of each other.
Where does B°7 appear in famous music?: Beethoven's "Pathétique" Sonata Op. 13 (which opens with this exact chord), Mozart's C minor sonata K. 457, and Schubert's C-minor literature all use B°7 as the primary cadential preparation.