The open chord
Frets, low E to high E: x 3 2 0 1 0 — notes x C E G C E. The root (C) sits on the 3rd fret of the A string; the 5th string is the lowest voiced note, so the 6th string is muted.
| String | Fret | Note | Role |
|---|---|---|---|
| 1 (high E) | 0 | E | 3rd |
| 2 (B) | 1 | C | root (octave) |
| 3 (G) | 0 | G | 5th |
| 4 (D) | 2 | E | 3rd |
| 5 (A) | 3 | C | root |
| 6 (low E) | x | — | muted |
As a movable shape
Slide the whole shape up so the root on the A string lands on the note you want. The open strings that were part of the chord need to be barred or fretted — that is why the full C-shape is often played as a partial voicing on the top four strings.
Example — D major as a C-shape (move everything up two frets):
| String | Fret | Note | Role |
|---|---|---|---|
| 1 (high E) | 2 | F# | 3rd |
| 2 (B) | 3 | D | root (octave) |
| 3 (G) | 2 | A | 5th |
| 4 (D) | 4 | F# | 3rd |
| 5 (A) | 5 | D | root |
| 6 (low E) | x | — | muted |
To find the shape for any major chord: place your 3rd finger on the root on the A string, then fret the rest of the shape relative to that root.
Where it sits on the neck
The C-shape sits between the D-shape (below) and the A-shape (above) for a given chord. For C major, the C-shape is in open position and the A-shape appears three frets higher (barred at the 3rd fret).
Common variants
Cm-shape (minor)
Lower the 3rds by a semitone. The E on the D string becomes Eb, and the E on the high E string becomes Eb (fret 1 → open becomes impractical, so this is almost always played as a partial barre in moved-up form).
C7-shape (dominant 7th)
Add a Bb (fret 3 on the G string, replacing the open G, for example) to turn the shape into a dominant 7th voicing.
Cmaj7-shape
Keep the open B (or its moved-up equivalent) — that is already the major 7th above C — and omit the high-E 3rd to avoid an extra C on top. The result is a very common jazz/pop C-shape voicing.