About the Guitar Tuner
This online guitar tuner listens to your instrument through the microphone of your phone or computer and shows with a needle whether the string is sharp or flat. When the needle sits in the green zone in the middle (±5 cents), the string is in tune. No app, no sign-up – it runs right in your browser.
Choose standard tuning (EADGBE), Drop D, half step down, 4-string bass, ukulele or violin, and set the reference pitch A4 anywhere from 430 to 450 Hz. The audio is analyzed locally and is never recorded or uploaded.
How to use
- Pick your instrument and tuning under Instrument & tuning – Guitar standard if you are unsure.
- Press Start tuning and allow microphone access when your browser asks.
- Pluck one string and watch the needle. Left (−) means flat, so tighten the string; right (+) means sharp, so loosen it. When it turns green, move to the next string.
- To tune by ear, tap a string button to hear its reference tone, or switch to Manual to lock onto one string.
Standard tunings and frequencies (A4 = 440 Hz)
| Tuning | Notes (low → high) | Frequencies (Hz) |
|---|---|---|
| Guitar standard | E2 · A2 · D3 · G3 · B3 · E4 | 82.41 · 110.00 · 146.83 · 196.00 · 246.94 · 329.63 |
| Guitar Drop D | D2 · A2 · D3 · G3 · B3 · E4 | 73.42 · 110.00 · 146.83 · 196.00 · 246.94 · 329.63 |
| Guitar half step down | E♭2 · A♭2 · D♭3 · G♭3 · B♭3 · E♭4 | 77.78 · 103.83 · 138.59 · 185.00 · 233.08 · 311.13 |
| Bass 4-string | E1 · A1 · D2 · G2 | 41.20 · 55.00 · 73.42 · 98.00 |
| Ukulele | G4 · C4 · E4 · A4 | 392.00 · 261.63 · 329.63 · 440.00 |
| Violin | G3 · D4 · A4 · E5 | 196.00 · 293.66 · 440.00 · 659.26 |
Guitar strings are listed from the 6th (thickest) to the 1st: E–A–D–G–B–E. Standard ukulele tuning is re-entrant (high G): the 4th string G is higher than the C string.
Tips for accurate tuning
- Tune up to the note. If you are sharp, drop below the target first, then tighten up to it – the string holds its pitch better.
- Right after you pluck, the note rings slightly sharp. Read the needle once the sound settles.
- A quiet room helps. Hold your phone close to the sound hole or headstock – headphones are not required.
- Check all strings a second time: changing tension on one string slightly bends the neck and shifts the others.
- New strings stretch and go flat quickly, so retune a few times.
What are cents and the A4 reference?
A cent is 1/100 of a semitone. Most people can’t hear a difference under ±5 cents. The offset is 1200 × log₂(measured ÷ target) – for example, 445 Hz is about +20 cents above 440 Hz.
The A4 reference is normally 440 Hz. Many orchestras tune to 442 Hz, and some players prefer 432 Hz. Changing it moves every string’s target, and your choice is saved.
FAQ
I allowed the microphone but no note shows up.
Pluck a little harder and bring the phone closer to the instrument. Make sure no other app is using the mic and that a Bluetooth headset isn’t taking over as input. In-app browsers (Instagram, Facebook) often block the mic – open the page in Chrome or Safari.
The tuner shows the right note but the wrong octave.
Strings with strong overtones are occasionally detected an octave higher. Pluck the open string more softly (not a harmonic). The note letter is still correct, so you can follow the needle.
What is the difference between Auto and Manual?
Auto highlights the string closest to the note it hears. Manual locks the target to the string you tapped, which helps when a string is so far off that it would be mistaken for a neighbouring one.
Is my audio recorded or sent anywhere?
No. The sound is analyzed in real time inside your browser and is never stored or uploaded. Stopping the tuner or closing the page releases the microphone immediately.