Free Online Guitar Tuner

It taps into your device microphone using modern Web Audio API. Our browser engine processes sound waves in real time via high-resolution autocorrelation to detect your string fundamental frequency, so you can tune acoustic or electric guitars without extra gear.

Brand new strings need stretching, and changes in temperature or humidity cause neck wood to expand or contract. Also, make sure you tune UP to pitch rather than down so the tuning peg gears lock tight without slack.

Standard concert pitch sets A4 to 440 Hz, which is the global music standard for guitars, pianos, and orchestras. Setting A4 to 432 Hz lowers overall pitch slightly for a warm, vintage feel popularized by certain meditative acoustic styles.

Hold your phone or laptop microphone close to the guitar soundhole or bridge pickup, and increase our built-in Noise Gate slider. This cuts out ambient background chatter and lets only your direct string pluck trigger the needle.

A cent is a logarithmic musical measurement where 100 cents equal one half-step (semitone). Our tuner marks green when you are within ±3 cents of pure pitch, giving you studio-grade intonation across the whole fretboard.

Not at all. guitartuner.si runs entirely inside Chrome, Safari, Firefox, Edge, and iOS/Android mobile browsers with 100% on-device audio privacy.