Open C Tuning
Open C tuning is C – G – C – G – C – E, from the 6th string to the 1st. Strummed open, the guitar plays a C major chord with a very deep bass. Use the tuner below to tune each string.
Your browser will ask to use the microphone. Choose Allow.
✓ All strings in tune
Tap a string to hear it and tune only that string. Audio is analysed on this device and never uploaded. How it works →
- What it does
- Preset to Open C: hears each string, shows which one and how far to turn it
- What it does not do
- Record or upload audio · detect chords
- Reference pitch
- A4 = 440 Hz, adjustable 415–466 Hz
- Tested with
- 58 studio recordings of 11 instruments (right note on about 95% of frames at normal volume) and test tones from B0 to C6
- Made by
- The Appcellent team
- Updated
- November 2026
Tuner not hearing you?
- Allow the microphone. If you blocked it: in Chrome or Edge, click the icon left of the address bar → Microphone → Allow, then reload. In Safari on iPhone, tap aA → Website Settings → Microphone → Allow. In Firefox, click the crossed-out microphone in the address bar. On a Mac, also check System Settings → Privacy & Security → Microphone for your browser.
- Open the page in Safari or Chrome. In-app browsers (Instagram, Facebook, TikTok) often block the microphone.
- Play one note at a time, louder. Hold your phone or laptop close to the instrument and let the string ring. A quiet room helps.
- Wrong octave or jumping notes? Let the attack fade for a moment — the reading settles once the note is steady.
- No microphone at all? Tap a string button to hear its note and tune by ear.
Open C notes and frequencies
Open C tuning is 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), from the 6th string to the 1st. From standard tuning (E A D G B E): Lower the 6th string from E to C (2 whole steps); lower the 5th string from A to G (a whole step); lower the 4th string from D to C (a whole step); raise the 2nd string from B to C (a half step). The 3rd and 1st strings stay the same.
| String | Note | Frequency | From standard |
|---|---|---|---|
| 6 | C2 | 65.41 Hz | E2 → C2 · down 2 whole steps |
| 5 | G2 | 98.00 Hz | A2 → G2 · down whole step |
| 4 | C3 | 130.81 Hz | D3 → C3 · down whole step |
| 3 | G3 | 196.00 Hz | no change |
| 2 | C4 | 261.63 Hz | B3 → C4 · up half step |
| 1 | E4 | 329.63 Hz | no change |
About Open C tuning
Open C is used in fingerstyle, folk and ambient guitar for its big, ringing low end. The 6th string drops four semitones from E to C, which gives the tuning its depth.
The low C string gets quite loose on a normal set, so pluck it gently. Some players use a slightly heavier 6th string when they stay in open C.
How to tune to Open C
- Press Start tuner above and allow the microphone. The tuner is already set to Open C.
- Play one string at a time. The tuner shows which string it hears and whether to tune up or down.
- Turn the peg until the needle is centered and the note turns green. Tap a string button to hear its target note.
- After all strings are done, check them again — changing tension on one string pulls the others slightly.