Fdim Chord on Guitar
Fdim = F – G# – B (Root, Minor 3rd, Tritone)
Fdim breaks from the E-shape barre pattern the rest of this set follows, since diminished triads shrink both the third and fifth, producing a more compact shape at the same demanding first-fret position — with the B string muted outright rather than fretted.
F, G#, and B make up the triad — root, minor third, diminished fifth. As the leading-tone triad (vii°) of Gb(F#) major, Fdim carries strong forward pull toward that tonic, the classic function diminished chords serve: built on the seventh scale degree, they create tension that all but demands resolution up a half step to the chord that follows.
Fingerings
Barre (1st fret)
How to Practice It
Two extra fingers are needed, on the A and D strings, while the B string is deliberately left unfretted and muted rather than played — getting that mute clean takes real care at this particular fret, since the tight first-fret spacing makes it easy for an unintended string to buzz. Because diminished triads are less common in typical guitar rock and folk repertoire, this is also a good chord for training the ear to recognize that particular unstable, searching quality on sight.
Common Progressions
- Fdim – Gb (vii° – I, the classic leading-tone resolution)
- Ebm – Fdim – Gb (vi – vii° – I)
- Cb – Fdim – Gb (IV – vii° – I)
- Gb – Fdim – Gb (a passing diminished color around the tonic)
FAQ
- Why is Fdim's shape different from the other F-rooted barre chords?
- Diminished triads shrink both the third and fifth compared to a major chord, which changes the fret pattern noticeably and also requires muting the B string rather than fretting it.
- Where does Fdim resolve?
- Up a half step to Gb(F#) major, since it functions as the leading-tone diminished triad (vii°) of that key, and diminished chords built on the seventh degree characteristically resolve upward into the tonic that follows.
- Is Fdim hard to play given the first-fret position?
- It's a fairly compact shape in terms of note count, needing only two extra fingers, but muting the B string cleanly at this particular fret takes some practice since the tight spacing makes stray buzzing more likely.
- How common are diminished triads in guitar-based songwriting?
- Less common than major, minor, or seventh chords generally, since their strong, unresolved tension makes them better suited to brief passing moments than sustained harmony.
- Why does a diminished triad sound so unstable?
- Stacking two minor thirds on top of the root produces a diminished fifth instead of a triad's usual stable perfect fifth, and that unstable interval is exactly what gives diminished chords their characteristic searching, tension-filled color.
- Does Fdim ever function outside of Gb major?
- Yes — the same triad also serves as vii° of Gb harmonic minor in certain minor-key contexts, since both keys share F as their leading tone, giving this chord a second plausible resolution.
- Is there a more common way this exact sound appears in practice?
- Guitarists more often reach for the diminished seventh (Fdim7) rather than the plain diminished triad, since the fuller four-note chord is the more standard voicing in jazz and classical-leaning guitar contexts.
Fdim on other instruments: Fdim on Piano, Fdim on Ukulele. Related: how chords are built, chord finder.