Chord & FretC#7 · Ukulele
A doorbell ringing with nobody answering. A phone buzzing face-down on the table. Some things only exist to be resolved — C#7 is their musical version. Tap the player below and feel the unfinished business.
Listen first
What you just heard
Why does it sound unfinished? Inside C#7, two notes are at odds: F and B. Now listen to the arpeggio, one note at a time and catch the second and the last note — the distance between them is the tritone, the tensest interval tonal music knows. C# and G# keep the house standing while those two argue inside it. And an argument, you know, demands a resolution.
Now it's your hands' turn
On the ukulele, the high reentrant G makes every shape light — and with four strings, every note is exposed. So grab the first position below; it's also the easiest one to play. Now the experiment that explains this chord better than any explanation: play C#7, let it ring a moment, then play F#. Felt the door close? Do it again. That relief is the reason this chord exists.
1 more shape of this chord on the neck
Chord & Fret Pro maps over 200,000 voicings and inversions — hear and play them all.
Precision Tuner — Before you play these shapes, get in tune — chromatic tuner and reference tones · try it in Chord & Fret
Save the positions below for when the blues calls: over there, this chord is the house language.
Every shape of C#7 lives in Chord & Fret Pro — 4 instruments, 16 tunings, 41 chord types and 57 scales, in every key. Start free. Unlock everything with Pro. 100% offline. Made by musicians, no ads.
Left-handed? Mirror's right here
What is C#7?
C#7: C# Major with Seventh. The notes are C#, E#, G#, B (fixed-do: Do#, Mi#, Sol#, Si) — the degrees 1–3–5–b7.
Where this chord lives
Its job is fixed: C#7 is a dominant, and dominants live as VII7 in D# minor, V7 in F# major. Translation: wherever it shows up, the music is about to move. A chart full of 7th chords is a song that won't sit still.
Transpose & Capo — Need it in another key? Move the whole chart and find the easiest capo · open in Chord & Fret
Identify Chord — Found a shape on your own fretboard? The app names it back · use it in Chord & Fret
Where it tends to go
Treating C#7 as the home chord (I) of its key, it tends to go toward the pre-dominant (D#m / F#) or the dominant (G# / B#°) — and the dominant pulls back home. Typically, not a rule.
When you want to go further
For soloing, C# Mixolydian (C# D# E# F# G# A# B · 1 2 3 4 5 6 b7: the major scale with a lowered seventh — the blues accent); C# Lydian dominant (C# D# E# F## G# A# B · 1 2 3 #4 5 6 b7: a mixolydian with a raised fourth: the dominant in formalwear) cover the whole chord. And look at the first swap on the list below: that's the famous tritone substitution, a second dominant hiding three whole steps away, the one arrangers reach for when they want to arrive at the same place by a prettier road.
C# Mixolydian
4 more scale positions on the neck
That's over 35,000 mapped scale shapes in Chord & Fret Pro, ready to play.
The same C# Mixolydian in its main shapes along the neck — pick whichever position sits under your hand. The rings mark the guide notes (the 3rd and 7th) that carry this chord's color.
Improvising in context
To improvise over C#7 as home, the C# Mixolydian scale covers it whole — it contains every note of the chord. And when the dominant (G#) pulls back, the leading tone C is the note that wants to resolve home.
Swaps that work:
- G7 — Tritone substitution (shared 3rd–7th tritone)
- Abm7 — Forms a II–V: precede with this ii
- Ddim7 — Passing diminished (ascending)
Reharmonize — Want richer substitutions? Reharmonize the progression in a tap · see it in Chord & Fret
The same chord, dressed for jazz
Jazz Lab — Drop 2, drop 3 and shell in any key — the Jazz Lab opens them all · use it in Chord & Fret
You already know how this sentence ends. The period after C#7 is called F# — go there and close it with your own fingers.