F#dim Chord on Guitar
F#dim = F# – A – C (Root, Minor 3rd, Tritone)
F#dim breaks from the pattern the other F#-rooted chords in this family follow: instead of a full six-string barre, one string (the A string) has to be muted entirely, because a plain diminished triad's three notes don't distribute evenly across six strings the way a major or minor triad's do without either doubling awkwardly or muting something.
The sounding notes are F#-A-C: root, minor third, and diminished fifth — a stack of two minor thirds that produces the most unstable, restless triad in standard tonal harmony. Diminished triads almost never function as a destination; they're passing or leading chords, most commonly the viio of a major key, built on the seventh scale degree and driving hard toward the tonic. F#dim is viio of G major, giving it a strong pull toward G, and it also shows up as a chromatic passing chord sliding between two diatonic chords a whole step apart.
Fingerings
Barre (2nd fret)
How to Practice It
Because the A string needs to stay silent, spend extra time on muting technique here rather than fretting technique — let the fretting-hand thumb or an unused finger lightly touch that string so it doesn't ring out accidentally during a strum. Practice resolving F#dim to G major to hear the leading-tone pull that defines what diminished triads are for; playing it in isolation, without that resolution, misses the point of the chord entirely.
Common Progressions
- F#dim – G (viio – I in G major, the classic leading-tone resolution)
- Em – F#dim – G (vi – viio – I in G major, a stepwise ascent)
- G – F#dim – Em (I sliding chromatically down through a passing diminished chord to vi)
- C – F#dim – G (IV – viio – I, another common leading-tone cadence)
FAQ
- Why does F#dim require muting a string instead of using all six?
- A diminished triad has only three distinct notes, and this shape's most natural fingering leaves the A string sitting on a pitch that doesn't belong to the chord, so it has to be silenced rather than fretted or left open.
- What does F#dim resolve to?
- Most commonly to G major, since F#dim functions as the viio (leading-tone diminished triad) of G major, and that resolution — up a half step to the tonic — is the chord's defining harmonic behavior.
- Is F#dim ever a destination chord rather than a passing one?
- Rarely — diminished triads are inherently unstable-sounding, built from two stacked minor thirds with no strong consonant frame, so they're used almost exclusively to create tension that resolves elsewhere rather than to settle a progression.
- How does F#dim differ from F#dim7?
- F#dim is a three-note triad (root, minor third, diminished fifth); F#dim7 adds a fourth note, the diminished seventh, stacking one more minor third on top and making the chord fully symmetrical.
- Is F#dim hard to switch into from other chords?
- Not especially — the shape is compact and low on the neck, and the main challenge is remembering to mute the A string cleanly rather than any unusual stretch or barre demand.
F#dim on other instruments: F#dim on Piano, F#dim on Ukulele. Related: how chords are built, chord finder.