GuitarTuningsGuitartunings.

Open C Guitar Tuner

Open C
±0
C
Target: 65.4 Hz
-50WAITING+50
Waiting for sound
C65
G98
C131
G196
C262
E330

How to Tune to Open C

A massive, wide-interval tuning with a booming low C that produces an incredibly rich, resonant open C major chord. Open C (C-G-C-G-C-E) spans nearly four octaves and creates a huge, ambient sound beloved by acoustic virtuosos and heavy progressive rock artists alike. John Butler's "Ocean" and Devin Townsend's wall-of-sound productions both rely on this tuning.

Start in standard tuning (E-A-D-G-B-E) and change 4 of 6 strings:

StringStandardTargetWhat to do
String 6E2C2Tune down 4 semitones
String 5A2G2Tune down a whole step
String 4D3C3Tune down a whole step
String 3G3G3Leave as is
String 2B3C4Tune up a half step
String 1E4E4Leave as is
Printable Open C chart (PNG / PDF)
Fun Fact

John Butler's live performance of "Ocean" in Open C tuning has become one of the most-watched guitar videos on YouTube, with the 2012 Federation Square performance accumulating tens of millions of views. The piece is a 12-minute improvised solo that showcases the tuning's extraordinary range, from thundering bass lines to shimmering harmonics.

String Tension & Setup Tips

Recommended Gauge:Medium-heavy strings for acoustic (.013-.056) to maintain tone on the very low C string. The low E dropped to C requires extra mass for clarity. For electric, .012-.054 works well. The B string tuned up to C is only a half step and safe with any gauge.

Gear for Open C

Tools that make tuning to C - G - C - G - C - E easier.

D'Addario Universal Micro Headstock Tuner

A headstock tuner makes switching in and out of this tuning quick, even on stage or without a mic.

View tuner

D'Addario Pro-Winder (winder + cutter)

Retuning 4 strings means a lot of turning — a winder speeds it up and trims new strings too.

View winder

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Open CIntermediate
C - G - C - G - C - ENo Capo
Song Details
Open CIntermediate
C - G - C - G - C - ENo Capo
Song Details
Open CIntermediate
C - G - C - G - C - ENo Capo
Song Details
Open C TuningIntermediate
C - G - C - G - C - ENo Capo
Song Details

Frequently Asked Questions

Will my B string break?
Very unlikely. Tuning the B string up a half step to C is a very small change — the string tension increases by only about 6%. This is well within the safe range for any standard string gauge. The real concern with Open C is the opposite end: the low E dropped to C needs a heavy enough gauge to sound clear.
How to tune to Open C on acoustic guitar?
From standard tuning: drop E to C (two whole steps), drop A to G (one whole step), drop D to C (one whole step), keep G as-is, tune B up to C (one half step), keep high E as-is. Most strings go down, so the overall tension is lower than standard. Use a heavier low string (.056+) for a clear, defined bass note.
What tuning is Ocean by John Butler in?
"Ocean" by John Butler Trio is in Open C (C-G-C-G-C-E). Butler uses a 12-string guitar for the studio recording and often performs it on an 11-string custom instrument. The tuning's wide intervals — spanning from the low C to the high E — give the piece its extraordinary dynamic range.
What are the frequencies for Open C?
C2 = 65.41 Hz, G2 = 98.00 Hz, C3 = 130.81 Hz, G3 = 196.00 Hz, C4 = 261.63 Hz, E4 = 329.63 Hz. The three C notes span three octaves, and the two G notes span two octaves, creating a massive, reinforced harmonic foundation.