What is Open C tuning?
Open C tunes the open strings to a C major chord: C–G–C–G–C–E, low to high. Four strings move from standard. The 6th drops two whole steps from E to C, the 5th and 4th each drop a whole step, and the 2nd rises a half step from B to C. The 3rd and 1st strings stay at G and E.
The low C is the lowest note of any common guitar tuning, and with the root on three strings and the fifth on two, the open chord is enormously wide. It is a fingerstyle and acoustic tuning above all — long ringing basses under a melody on the top two strings.
The highlighted strings are the ones that move. Tap a string to hear its target.
String notes and frequencies
The exact pitch of each open string at concert pitch, A = 440 Hz — the numbers a strobe or a frequency counter would show. The tuner above works from the same targets.
| String | Note | Frequency | From standard |
|---|---|---|---|
| 6th | C2 | 65.41 Hz | E2 → C2, 4 semitones down |
| 5th | G2 | 98.00 Hz | A2 → G2, 2 semitones down |
| 4th | C3 | 130.81 Hz | D3 → C3, 2 semitones down |
| 3rd | G3 | 196.00 Hz | unchanged |
| 2nd | C4 | 261.63 Hz | B3 → C4, 1 semitone up |
| 1st | E4 | 329.63 Hz | unchanged |
Getting to Open C
- Lower the 6th string from E to C. Four semitones — the dial passes D♯, D and C♯ on the way down. The string will feel very slack; that is expected.
- Lower the 5th string from A to G, and the 4th from D to C. The 4th string should end exactly an octave above the 6th.
- Raise the 2nd string from B to C. One semitone up — the only string that tightens. It ends an octave above the 4th string.
- Strum, then go round again. With this much tension taken off the bass side, the neck moves. A second pass is necessary, not optional.
Where the notes are
The first five frets of every string in this tuning. Each fret is one semitone, so this is also how to check a string against its neighbour: find the fret where the lower string plays the higher string’s open note.
| String | Open | Fret 1 | Fret 2 | Fret 3 | Fret 4 | Fret 5 |
|---|---|---|---|---|---|---|
| 1st | E | F | F♯ | G | G♯ | A |
| 2nd | C | C♯ | D | D♯ | E | F |
| 3rd | G | G♯ | A | A♯ | B | C |
| 4th | C | C♯ | D | D♯ | E | F |
| 5th | G | G♯ | A | A♯ | B | C |
| 6th | C | C♯ | D | D♯ | E | F |
Frequently asked questions
Why does my low C read sharp when I pluck it hard?
A slack string is stretched noticeably by a hard pluck, and stretching raises its pitch for the first moment of the note before it settles. Tune it with the gentle pluck you will actually play it with, and read the dial after the first half second.
Is Open C the same as C standard?
No. C standard lowers all six strings by two whole steps and keeps the intervals of standard tuning (C–F–A♯–D♯–G–C), so chord shapes are unchanged. Open C retunes the strings to the notes of a C major chord, so the shapes are all different and the open strings are a chord in themselves.
What chords are easy in Open C?
C is every string open. F is a straight barre at the 5th fret and G at the 7th — the three chords of the key of C. The major third of the chord is on the top string alone, so leaving that string out gives a chord that is neither major nor minor.
For everything else about tuning the instrument itself — strings that slip, pegs, and what the dial is telling you — see the guitar tuner and the standard guitar tuning this one is measured from.
Common chord shapes in Open C tuning
Where the everyday chords fall on a guitar tuned this way. Each shape is found by searching this tuning’s own strings for the frets that sound the chord — nothing here is copied from a standard-tuning chart — and each plays when you press it.
- G777777
- C000000
- D222222
- Ax21210
- E444444
- Emxx4443
- Amx20200
- Dmxx2221