C dominant 7 guitar chord (C7)

How to play C7

Finger numbers run 1 for the index to 4 for the little finger. String names are given as players say them — the low E is the thickest string (the 6th) and the high E is the thinnest (the 1st).

1. 1st finger (index) — 1st fret, B string
2. 2nd finger (middle) — 2nd fret, D string
3. 3rd finger (ring) — 3rd fret, A string
4. 4th finger (little) — 3rd fret, G string

• Play open: high E (1st) — strum it without fretting anything.
• Leave out: low E (6th) — start the strum below it, or damp it with the side of the thumb.

Notes and intervals in C7

C7 is built from 4 notes: C, E, G and B♭.

• C — the root (R)
• E — the major 3rd (3)
• G — the perfect 5th (5)
• B♭ — the flat 7th (b7)

Across the six strings the shape sounds C · E · B♭ · C · E from low to high, so some notes are doubled in different octaves — that is what gives an open guitar chord its width compared with the same chord on a keyboard.

This voicing leaves out the G entirely. That is normal for a 7th chord on guitar: with only six strings something has to go, and the 5th is the note the ear misses least.

What C7 is used for

C7 adds a B♭ on the 3rd fret of the G string to the C shape, which is what forces the little finger into action. It is the V7 of F and the opening chord of a blues in C. This voicing leaves out the 5th (G) altogether: dominant 7th chords give up their 5th readily because the flat 7th is what creates the pull.

Common mistakes with C7

• Avoiding the little finger. C7 needs all four; putting the ring finger on the G string collapses the shape and mutes the B string.
• Muting the open high E, usually because the little finger has arrived flat rather than on its tip.
• Strumming the 6th string — the root C sits on the 5th string.

Chords that go with C7

Same-root variations first, then the chords a fourth and a fifth away — the shapes C7 is most often played alongside.

• C major
• C add9
• F major
• G major