The standard grips this chord is usually shown with.
C7 is C, E, G and Bb — C with the flat seventh added on top.
It sounds restless and pointed at something. The third and the flat seventh are a tritone apart and each moves by a semitone into the next chord; that is the engine of a cadence, and the whole vocabulary of the blues.

| C | E | G | Bb |
|---|---|---|---|
| 1 | 3 | 5 | ♭7 |
Dominant — it points a fifth down.
Also written Cdom7 or C dominant 7. The same chord either way; which spelling you meet depends on who wrote the chart.
C7 in root position puts C in the bass, which is the chord as it is spelled: the note it is named after underneath everything else.
6 of C7’s 7 common shapes do this: x32310, x35353, 875556, 8-10-8-9-8-8, x-x-10-12-11-12, x-15-14-15-13-x.
Start with x32310 — no barre and 1 open string. 1 of the 7 shapes here sits in open position. 4 of the 7 need a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x32310 | open position | C, root position | E | 1 open string |
| x35353 | 3rd fret | C, root position | G | barred |
| xx5556 | 5th fret | G, 2nd inversion | Bb | barred |
| 875556 | 5th fret | C, root position | Bb | barred |
| 8-10-8-9-8-8 | 8th fret | C, root position | C | barred |
| x-x-10-12-11-12 | 10th fret | C, root position | E | all fretted |
| x-15-14-15-13-x | 13th fret | C, root position | C | all fretted |
The same notes rebuilt from scratch give 5 shell, 15 drop 2, 10 drop 3 and 6 open string voicings, each on its own page.
Tensions. A shell of C7, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Db), the 9 (D), the #9 (D#), the #11 (F#), the b13 (Ab) and the 13 (A).
C7 is the V of F, and that is where it goes if it goes anywhere: the third and the flat seventh are a tritone apart, and both resolve by a semitone into F.
Voice by voice, C7 → F. 2 voices move by a semitone, and one note is common to both chords.
| In C7 | Moves | In F |
|---|---|---|
| C, the root | stays where it is | C, the fifth |
| E, the major third | rises a semitone | F, the root |
| G, the fifth | falls a whole tone | F, the root |
| Bb, the flat seventh | falls a semitone | A, the major third |
In which keys. Every note of C7 belongs to D minor (the ♭VII) and F major (the V, the dominant).
Every note of C7 is in C mixolydian, C lydian dominant and C half-whole diminished.
Change one note of C7 and you have C (drop the flat seventh), Cmaj7 (the flat seventh becomes a major seventh), Cm7 (the major third becomes a minor third), Cadd9 (the flat seventh becomes a ninth), C6 (the flat seventh becomes a sixth) or C7sus4 (the major third becomes a fourth).
C7 is a dominant chord — root, major third, fifth, minor seventh. Dominant seventh chords on every root.
On C7’s sound and use this page follows Edward Aldwell & Carl Schachter, Harmony and Voice Leading (Schirmer / Cengage, 4th ed., 2011). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.