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Built and maintained by the GuitarTuna team — trusted by 100M+ musicians worldwide.

Tuning one instrument in particular?

The tuner above works for all of them. These pages add a headstock diagram, the standard tuning for that instrument, and string by string guidance.

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How to use the online tuner

Press the tune button and allow microphone access when your browser asks. Play one note and let it ring long enough for the pitch to settle. The tuner names the note it heard and shows its octave, so you do not have to tell it what you are playing first.

The number on the needle is the distance from that pitch in cents, where one hundred cents is a semitone. A positive reading means you are sharp and need to release tension. A negative reading means you are flat and need to add tension. When the needle settles in the middle it turns green and you will hear a short confirmation tone.

Because nothing is locked to a preset, the tuner is happy with any pitch you give it. That makes it useful for open tunings, capo positions, instruments that are transposed, brass and woodwind, and for checking whether a piano or a fixed pitch instrument has drifted.

Play single notes rather than chords. The pitch detection follows one fundamental at a time, so a strummed chord gives it several competing candidates and the reading will jump around. A quiet room helps too, since background noise adds partials that can pull the estimate off.

How the tuner works

The tuner runs entirely in your browser. When you grant microphone access, the audio stream is handed to an AudioWorklet, which is a small piece of code that runs on the browser audio thread rather than the main thread. Keeping it off the main thread is what stops the reading from stuttering while the rest of the page renders.

That worklet collects the incoming signal into blocks of 4096 samples. At a typical sample rate of 48 kHz each block covers a little under a tenth of a second, which is long enough to resolve low notes accurately and short enough that the display still feels immediate.

Each block is passed to a pitch detection routine compiled to WebAssembly. It estimates the fundamental frequency of the strongest note in the block and returns two things, the nearest note on the twelve tone scale expressed as a MIDI number, and how far the measured pitch sits from that note in cents. The page converts the MIDI number into a note name and octave, which is what appears in the middle of the dial.

Reference pitch is A4 at 440 Hz and every other note is derived from it using equal temperament, so each semitone is the twelfth root of two above the last. The needle is considered centred once the estimate is stable and within a narrow window of the target, which prevents it from flickering green on a note that is still moving.

No audio leaves your device. The microphone stream is analysed locally and discarded, nothing is recorded, and nothing is sent to a server. Closing the tab or switching away releases the microphone straight away.