Chord & FretC#7 · Guitar
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. Press play down there and feel the unfinished business.
Listen first
What you just heard
Why does it sound unfinished? Inside C#7, two notes are arguing: F and B. Go back to the audio and catch the arpeggio note by note 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 guitar, six strings give the chord room to breathe — some positions use them all, others ask you to mute the lowest ones. So grab the first position below; the position marked with ⭐ is the easiest to play. Now the experiment that explains this chord better than any explanation: play C#7, count to three, 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 · use it in Chord & Fret
The other positions earn their keep in blues and jazz, where this chord is practically the official language; learn them one at a time.
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. Free to start, no card needed.
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 · see it in Chord & Fret
Identify Chord — Found a shape on your own fretboard? The app names it back · try it in Chord & Fret
Where it tends to go
Treating C#7 as the home chord (I) of its key, it usually moves toward the pre-dominant (D#m / F#) or the dominant (G# / B#°) — and the dominant pulls back home. It's a tendency, not a law.
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, the twin dominant living three whole steps from here, the one arrangers reach for when they want to arrive at the same place by a prettier road.
C# Mixolydian
3 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 · open 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
The question this page asked has a one-click answer: F#. Don't end the day without playing both in a row.