F#dim Chord on Ukulele
F#dim = F# – A – C (Root, Minor 3rd, Tritone)
F#dim strips the triad down to two fretted notes: the G string at the second fret and the E string at the second fret, with the C and A strings left open, since open C and open A both happen to already be chord tones. The result is a diminished triad — root, minor third, and diminished fifth — built entirely from stacked minor-third intervals, one of the more compact shapes in this whole chord family despite its unusual harmonic sound.
F#dim has a specific, well-defined job in the key of G major: it's the vii° chord, built on the seventh scale degree, and diminished triads built on the leading tone are the classic passing chord used to connect a I chord to its relative or nearby harmony with maximum forward pull, since a diminished triad's inherent instability makes it want to resolve almost immediately. It shows up constantly as a brief passing chord between G and Am or between G and G's own first inversion, adding a moment of tension a plain major or minor chord can't supply. Because two of its four ukulele voicing's strings stay open, F#dim keeps more resonance than its harmonic tension might suggest — it doesn't sound harsh so much as unsettled, which is exactly the quality that makes it useful as a connector rather than a destination.
Fingerings
Open Position
How to Practice It
Both fretted notes land on the same fret number but on non-adjacent strings (G and E, with C between them left open), so this is a two-finger placement, not a barre — keep the index and middle fingers independent and make sure the open C string between them isn't muted by either. Because F#dim is almost always a passing chord, practice it in motion rather than as a held chord: try G to F#dim to Am, or G to F#dim back to G's first inversion, focusing on how quickly the hand can drop into and out of the shape. It's also worth knowing that diminished triads repeat every minor third, so this exact shape, moved up three frets, produces a different diminished chord with the same shape.
Common Progressions
- I – vii° – I6, a classic passing move within G major (G – F#dim – G/B)
- vii° – i, resolving F#dim into G minor for a modal-interchange color
- vi – vii° – I, using F#dim as a connector into a G major cadence (Em – F#dim – G)
- F#dim as a chromatic passing chord between G and Am
FAQ
- What key does F#dim naturally belong to?
- G major — F# is that key's seventh scale degree, and the diminished triad built on it (vii°) is the classic passing chord used to connect G to nearby harmony with strong forward pull.
- Why does F#dim only need two fingers?
- The C and A strings are already chord tones in their open positions, so only the G and E strings need fretting, both at the second fret on non-adjacent strings.
- Is F#dim ever used as a chord to linger on?
- Rarely — diminished triads are inherently unstable and are almost always used as brief passing or connecting chords rather than places a progression settles.
- Does the F#dim shape work for other diminished chords?
- Yes — because diminished chords repeat every three frets (a minor third), sliding this same two-finger shape up or down by three-fret increments produces the other diminished chords sharing the same four notes.
F#dim on other instruments: F#dim on Guitar, F#dim on Piano. Related: how chords are built, chord finder.