Does C#7 resolve to F# major or F# minor?

Either, depending on context — a dominant seventh chord's job is to create tension that resolves to the tonic built on the same root a fourth above, and that tonic can be major or minor. C#7 works convincingly as the V7 of both F# major and F# minor.

How many black keys does C#7 use?

Two — C# and G#. The other two notes, F and B, are white keys, giving the chord a genuinely mixed hand geography rather than leaning mostly toward one key color the way some other dominant sevenths do.

What interval creates the tension in C#7?

The tritone between F and B, the chord's third and flattened seventh. That interval is the same distance in both directions (six semitones), which is exactly why it feels so unstable and wants to resolve outward toward F# major or minor.

Can C#7 be used outside of F#-related keys?

Yes — like any dominant seventh, C#7 can also function as a secondary dominant, briefly tonicizing F# in the middle of a progression that's centered on a completely different key, a common device for adding a moment of harmonic color and pull.

← Piano Chords

C#7 Chord on Piano

C#7 = C# – F – G# – B (Root, Major 3rd, Perfect 5th, Minor 7th)

C#7 takes the two-black-one-white shape of C# major and adds a fourth note, B, giving the notes C#, F, G#, and B — now split evenly between two black keys and two white keys. That added B is the flattened seventh, the note responsible for every dominant seventh chord's restless, want-to-resolve quality, and it sits comfortably as a white key just below the octave C#. As a dominant seventh, C#7 is the V7 of F# — whether the destination is F# major or F# minor depends on the surrounding music, since a dominant seventh chord resolves convincingly to either the major or minor tonic built on the same root.

With two fingers on black keys and two on white, C#7 asks the hand to alternate terrain across the shape rather than committing entirely to one type of key — thumb on the black C#, then a white-black-white pattern isn't quite what happens here, but the mixed geography still means no finger can rely on a single "flat plane" feel the way an all-white chord allows. Harmonically, the tritone between F and B — the third and seventh of the chord — is what pulls this chord toward resolution, exactly as it does in every dominant seventh regardless of key. Because F# minor is the more sharp-heavy and commonly used destination in guitar- and vocal-friendly repertoire, C#7 shows up constantly as a strong pivot chord heading there, giving a progression real forward motion before landing on F# minor's own darker color. Notice, too, that the F in this chord is functioning as the raised leading tone of F# harmonic minor even though it's spelled and played as a plain white key — a good early example of how the notation on this site (sharp-only spelling) can obscure the "on paper" role a note is actually playing in the underlying key.

Voicings

Root Position

1st Inversion

How to Practice It

Build C#7 the same way as any dominant seventh: play the C# major triad first, then add the B with the pinky, checking that it lands on the white key just below the octave C# rather than sliding too far and catching the black key beside it. Practice resolving C#7 into F# minor and then, separately, into F# major, so your ear learns that this exact same four-note shape can lead to two different destinations depending on what comes next — that flexibility is one of the most useful things to understand about dominant seventh chords generally, not just this one. Once resolution feels natural, try holding C#7 static for several beats before resolving, to get comfortable with letting the tension sit rather than rushing to release it.

Common Progressions

C#7 – F#m (V7 – i in F# minor), a strong minor-key resolution
C#7 – F# (V7 – I in F# major), the same chord resolving to the major tonic instead
F#m – C#7 – F#m (i – V7 – i), C#7 used as a turnaround inside an F# minor progression
Bm – C#7 – F#m (iv – V7 – i, harmonic-minor cadence), the classic minor-key resolution with a raised leading tone
A – Bm – C#7 – F#m (III – iv – V7 – i), a longer build in F# minor landing on C#7 before home

FAQ

Does C#7 resolve to F# major or F# minor?: Either, depending on context — a dominant seventh chord's job is to create tension that resolves to the tonic built on the same root a fourth above, and that tonic can be major or minor. C#7 works convincingly as the V7 of both F# major and F# minor.
How many black keys does C#7 use?: Two — C# and G#. The other two notes, F and B, are white keys, giving the chord a genuinely mixed hand geography rather than leaning mostly toward one key color the way some other dominant sevenths do.
What interval creates the tension in C#7?: The tritone between F and B, the chord's third and flattened seventh. That interval is the same distance in both directions (six semitones), which is exactly why it feels so unstable and wants to resolve outward toward F# major or minor.
Can C#7 be used outside of F#-related keys?: Yes — like any dominant seventh, C#7 can also function as a secondary dominant, briefly tonicizing F# in the middle of a progression that's centered on a completely different key, a common device for adding a moment of harmonic color and pull.

C#7 on other instruments: C#7 on Guitar, C#7 on Ukulele. Related: how chords are built, chord finder.