C7 · Ukulele

You know when you climb stairs in the dark and count one step too many? Your foot hangs there, waiting for a floor that never came. Press play down there: C7 is that foot in the air.

Listen first

What you just heard

Why does it sound unfinished? Inside C7, two notes are arguing: E and A#. 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 — 3 open strings to help you; it's also the easiest one to play. Now the experiment that explains this chord better than any explanation: play C7, let it ring a moment, then play F. Felt the door close? Do it again. That relief is the reason this chord exists.

Precision Tuner — Before you play these shapes, get in tune — chromatic tuner and reference tones · try 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.

What is C7?

C7: C Major with Seventh. The notes are C, E, G, Bb (fixed-do: Do, Mi, Sol, Si♭) — the degrees 1–3–5–b7.

Where this chord lives

Its job is fixed: C7 is a dominant, and dominants live as VII7 in D minor, V7 in F major. Plainly: where it enters, the song is about to leave the room. 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 · open in Chord & Fret

Where it tends to go

Treating C7 as the home chord (I) of its key, it tends to go toward the pre-dominant (Dm / F) or the dominant (G / B°) — and the dominant pulls back home. Typically, not a rule.

Every shape of C7 lives in Chord & Fret Pro — 4 instruments, 16 tunings, 41 chord types and 57 scales, in every key. Start free. Unlock everything with Pro. Plays offline. Works offline, no account needed.

When you want to go further

For soloing, C Mixolydian (C D E F G A Bb · 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 Bb · 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.

Scale — The whole scale on the neck — in boxes or three notes per string, with an exercise and a tempo ramp · see it in Chord & Fret

Improvising in context

To improvise over C7 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 B is the note that wants to resolve home.

Swaps that work:

• Gb7Gb7Gb7Gb7 — Tritone substitution (shared 3rd–7th tritone)
• Gm7Gm7Gm7Gm7 — Forms a II–V: precede with this ii
• Dbdim7 — Passing diminished (ascending)

Reharmonize — Want richer substitutions? Reharmonize the progression in a tap · use it in Chord & Fret

You already know how this sentence ends. The period after C7 is called F — go there and close it with your own fingers.

Updated August 5, 2026