What notes are in an F diminished chord?

F diminished contains three notes: F (the root), A♭ (the minor third), and C♭ (the diminished fifth — same pitch as B).

Why is the fifth C♭ instead of B?

The diminished triad uses each of three letters in a stacked-thirds pattern. Starting from F, the letters go F-A-C; the fifth must be the C letter, which is C♭ when lowered a half step from C natural.

What key does F diminished come from?

F° appears most naturally in G♭ major (where it's the vii°) and as a chromatic chord in F major. It's rarer than the more common diminished triads.

Is F diminished the same as F#°?

No — they're different pitch classes. F° is F–A♭–C♭ (= B); F♯° is F♯–A–C. Different chords entirely.

F diminished chord — notes, intervals, and practice

F diminished — F, A♭, C♭ — is a chromatic chord rather than a diatonic one. The C♭ (enharmonic to B) gives the chord away as borrowed harmony or a passing chord. F° most often appears as a chromatic neighbour to F major, or briefly as a vii° in G♭ major.

Intervals

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

F→Abminor 3rd3 semitones
Ab→Cbminor 3rd3 semitones
F→Cbdiminished 5th6 semitones

On the keyboard

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

On the guitar

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

Common mistakes

The fifth is C♭, enharmonic to B natural. In sharp-key contexts, the chord is more often written as F° using B as the fifth letter — strictly speaking that violates the seven-letter rule, but in chord-symbol practice the substitution is common. In flat-key contexts (the chord's natural home), C♭ is the proper spelling.

In context

F° rarely appears as a tonic; it's a chromatic colour chord. The most common contexts are passing harmony between F major and G♭ major, or as a chromatic neighbour to F major in late-Romantic writing. The chord's identity depends heavily on its surroundings.

Drill it

The F diminished 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.

Open the Chord Trainer →Or try today's Etudle puzzle

Frequently asked

What notes are in an F diminished chord?: F diminished contains three notes: F (the root), A♭ (the minor third), and C♭ (the diminished fifth — same pitch as B).
Why is the fifth C♭ instead of B?: The diminished triad uses each of three letters in a stacked-thirds pattern. Starting from F, the letters go F-A-C; the fifth must be the C letter, which is C♭ when lowered a half step from C natural.
What key does F diminished come from?: F° appears most naturally in G♭ major (where it's the vii°) and as a chromatic chord in F major. It's rarer than the more common diminished triads.
Is F diminished the same as F#°?: No — they're different pitch classes. F° is F–A♭–C♭ (= B); F♯° is F♯–A–C. Different chords entirely.