Open C Tuner for Guitar
Open C tuning sets the guitar to C G C G C E, from the 6th string to the 1st (C2 up to E4), so the open strings ring a big C major chord. This open C tuner is our guitar tuner with Open C already selected: play a string and it shows the note, the cents and which way to turn.
String notes and frequencies
Guitar tuning, open C (6 strings): C2 G2 C3 G3 C4 E4, from 65.41 Hz to 329.63 Hz, with A4 = 440 Hz.
| String | Note | Frequency (Hz) |
|---|---|---|
| String 6 | C2 | 65.41 |
| String 5 | G2 | 98.00 |
| String 4 | C3 | 130.81 |
| String 3 | G3 | 196.00 |
| String 2 | C4 | 261.63 |
| String 1 | E4 | 329.63 |
How to use it
- Tap Turn on microphone and check that the Tuning menu shows Open C.
- Start with the 6th string: lower it from E to C, four semitones. Pluck gently and let it ring for a second before trusting the needle.
- Lower the 5th from A to G and the 4th from D to C, a whole step each. Raise the 2nd from B to C, a half step. The 3rd (G) and the 1st (E) stay where they are.
- Tap a string's button to lock the reading on it, and press Play to hear its reference note. Auto goes back to detecting whichever string you play.
- Do a second pass from the 6th string up: the neck relaxes as the bass strings lose tension.
Help and explanations
It is the lowest of the common open tunings. Five of the six strings are roots and fifths, C and G, with a single E on top for the major third, so the guitar sounds huge and droning. Acoustic fingerstyle players love it for that resonance, slide players use it for a deep sound, and rock players know it from songs like Bad Company's Can't Get Enough.
From standard to open C, string by string
6th string: from E2 down to C2 (65.41 Hz), two whole steps. 5th: from A2 down to G2 (98.00 Hz). 4th: from D3 down to C3 (130.81 Hz). 3rd: G3 (196.00 Hz), unchanged. 2nd: from B3 up to C4 (261.63 Hz), the only string that goes up. 1st: E4 (329.63 Hz), unchanged.
To check by ear, compare the octaves: the 12th-fret harmonic of the 6th string must match the open 4th, that of the 5th the open 3rd, and that of the 4th the open 2nd.
Chords and slide in open C
A straight barre or a slide gives a major chord at every fret: open, C; 5th fret, F; 7th fret, G; 12th fret, C again, an octave up. That is the I, IV and V of the key of C, enough for a blues or a folk song. The 1st string carries the only third of the chord, so a minor chord comes from playing it one fret below the barre: F minor is the barre at the 5th fret with the 1st string at the 4th.
Leave the 1st string out and the other five give C5, a power chord with no third. With a capo at the 2nd fret, every shape moves to the key of D.
Tips
- Tune each string up to the note from below: a string you tighten into pitch holds better than one you overshoot and loosen.
- Pick the low C lightly: a hard attack pushes a slack string sharp for a moment and the needle jumps.
- Three Cs and two Gs: if the tuner lights up the string with the same name, tap the button of the string you are tuning to lock the target.
- To go back to standard, choose Standard in the Tuning menu: raise the 6th, 5th and 4th strings and lower the 2nd a half step.
Frequently asked questions
What are the notes of open C tuning?
C G C G C E, from the 6th string to the 1st: C2 (65.41 Hz), G2 (98.00 Hz), C3 (130.81 Hz), G3 (196.00 Hz), C4 (261.63 Hz) and E4 (329.63 Hz), with A4 = 440 Hz.
How do I tune a guitar to open C?
From standard tuning, lower the 6th string two whole steps (E to C), the 5th a whole step (A to G) and the 4th a whole step (D to C), and raise the 2nd a half step (B to C). The 3rd and 1st stay. Strum all six at the end: you should hear a clean C major chord.
Is open C the same as C standard?
No. C standard keeps the usual intervals two whole steps lower, C F B♭ E♭ G C, so normal chord shapes still work. In open C the open strings already form a C major chord.
What songs use open C tuning?
Bad Company's Can't Get Enough is played in open C, and the tuning is popular in acoustic fingerstyle and slide. Led Zeppelin's Friends uses a close variant with an A on the 5th string (C A C G C E); for that one, retune the 5th string with the chromatic tuner.
Why does my low C buzz or sound out of tune?
Two whole steps below its normal pitch, the 6th string is very slack: it flaps on the frets and reads sharp on the attack. Pick softer and let the note settle before reading. Players who stay in open C often use a heavier set, or just a heavier 6th string, and check the intonation.
Open C or open D: which should I use?
Both put a major chord on the open strings. Open D (D A D F♯ A D) moves four strings by smaller steps and keeps more tension; open C goes a whole step lower and sounds darker. Pick the one that fits the song's key.