12-String Guitar tuner – Open C
C-C-G-G-C-C-G-G-C-C-E-E · Open
Press “Start tuner” – the browser will ask for microphone access. Sound is analysed on this device and never uploaded.
This free online tuner listens through your microphone and shows how close each string of your 12-String Guitar is to Open C tuning (C-C-G-G-C-C-G-G-C-C-E-E). Play a string, watch the needle, and turn the peg until the meter glows green. If you prefer tuning by ear, tap any string card to hear its reference tone.
About Open C tuning
Compared with Standard, Open C moves 8 strings. Some strings go up and others go down, so the total tension stays close to Standard while the shape of the fretboard changes completely.4 strings stay exactly where they were.
| String | Standard | Open C | Change |
|---|---|---|---|
| 1 | E2 | C2 | down 4 semitones |
| 2 | E3 | C3 | down 4 semitones |
| 3 | A2 | G2 | down 2 semitones |
| 4 | A3 | G3 | down 2 semitones |
| 5 | D3 | C3 | down 2 semitones |
| 6 | D4 | C4 | down 2 semitones |
| 9 | B3 | C4 | up 1 semitone |
| 10 | B3 | C4 | up 1 semitone |
Played open, the strings sound C-C-G-G-C-C-G-G-C-C-E-E – from C2 at the bottom to G4 at the top, a span of 2 octaves and 7 semitones.
Open C is re-entrant: the strings do not rise steadily in pitch, so the string nearest your thumb is not the lowest note available. That is deliberate, and it is a large part of why the instrument sounds the way it does.
Strummed open, with nothing fretted, the strings spell C. That is what makes a tuning like this useful for slide playing and drones – a full chord is one straight barre away at any fret. See C shapes in this tuning →
Dropping 4 semitones takes the tension down noticeably. A heavier set – or at least a heavier bottom string – keeps the intonation honest and stops the low string buzzing.
History
Where the Open C tuning comes from
Open C on a twelve-string gives a huge, piano-like drone. The American fingerstyle guitarist Leo Kottke, famous for his twelve-string records from 1969 onward, used open tunings of this kind extensively.
Other 12-String Guitar tunings
Standard
Drop
Chords for this tuning
How do I tune my 12-String Guitar to Open C?
Allow microphone access, pluck a string, and the tuner will detect it automatically. The needle shows whether the string is flat or sharp – adjust until the reading is within ±5 cents (C-C-G-G-C-C-G-G-C-C-E-E).
Which notes are used in Open C tuning?
Open C tuning for 12-String Guitar uses the notes C-C-G-G-C-C-G-G-C-C-E-E, listed from the lowest string to the highest.
Can I tune without a microphone?
Yes. Every string card plays a reference tone – tap it and match your string to the sound by ear.