Free Guitar Tuner

Worked example

Leave "Instrument / tuning" on "Guitar (standard EADGBE)", the default, and press "Start tuning". Allow the microphone and the display says "Play a note to begin". Pluck the low E string. The big readout shows the nearest note, say "E2", with "-30 cents" and "81.0 Hz" beneath it. The needle leans left of centre and an amber line says "E2 string: 30 cents flat, tune up". Tighten the string. Within 5 cents of 82.4 Hz the readout turns green, a badge reads "IN TUNE", and the line changes to "E2 string: in tune". Under "Play a reference tone" are six buttons, E2, A2, D3, G3, B3 and E4. Pressing one plays a sine tone at that pitch, and pressing it again stops it.

Which settings to use, and the limits

• Choose your instrument or tuning before you start. "Instrument / tuning" starts on "Guitar (standard EADGBE)" and remembers your last choice on this device. It has groups for Guitar (Drop D, half-step down, D standard, DADGAD, Open G, Open D, Open E, 7-string and baritone), Bass (4, 5 and 6 strings) and Other instruments (ukulele, ukulele low G, mandolin, banjo and violin). "Chromatic (any note)" shows only the nearest note. A tuning also names the nearest string: a low string at 73.4 Hz reads "D2 string: in tune" under Drop D, but "E2 string: 200 cents flat, tune up" under standard.
• Set the A4 reference to match your group or recording. "A4 reference: 440 Hz" has a slider and a number box that accept 430 to 450 Hz in steps of 1. A typed value outside that range is pulled back to the nearest end. The setting moves every note and every reference tone: at 442 Hz the E2 tone is 82.8 Hz instead of 82.4 Hz. It is not remembered, so it returns to 440 when you reload the page.
• Pluck one string and let it ring. The tuner reads one clear note at a time. It ignores very quiet sound, sound without a steady repeating pitch such as chords, taps and room noise, and anything below 27 Hz or above 2,000 Hz. The needle moves across a scale of minus 50 to plus 50 cents, the readout gives whole cents and the frequency to one decimal, and "IN TUNE" appears within 5 cents. The readout clears after a short gap of silence. The page asks the browser to switch off echo cancellation, noise suppression and automatic gain.
• Use reference tones to tune by ear. With a tuning chosen, "Play a reference tone" shows one button per string, such as E2, A2, D3, G3, B3 and E4. Press one to hear a sine tone at that pitch and press it again to stop. Only one plays at a time, and changing the tuning stops it. The tones need no microphone, so they work before you press "Start tuning" and when the microphone is unavailable. On Safari 16.4 and later the page asks for audio that ignores the silent switch.
• Check the low strings against the tuning. The bass presets are "Bass (EADG)", "5-string bass (BEADG)" and "6-string bass (BEADGC)". The lowest string, B0, is 30.9 Hz, above the 27 Hz floor of the detector. "7-string standard (BEADGBE)" starts at B1, 61.7 Hz, and "Baritone (BEADF♯B)" at the same note. If a low string will not register, play it harder and closer to the microphone rather than changing the tuning.
• On a phone, keep the tab in front. After "Start tuning" the page scrolls so the dial is fully on screen if part of it was off screen. If you switch to another app or tab, the tuner stops listening and releases the microphone, and it starts listening again when you return if it was on. Press "Stop" to release the microphone yourself. Hold the phone near the instrument and tune one string at a time.

Common problems and how to fix them

It says "No microphone was found. Plug one in or check that your device has one enabled."

The browser reported no audio input that fits the request. Plug in a microphone or headset, or switch one on in the device's sound settings, then press "Start tuning" again. The tuning picker and the "Play a reference tone" buttons still work without a microphone, so you can tune by ear in the meantime.

It says "Microphone access was refused. Your browser will not ask again until you allow it in site settings."

The browser refused the microphone, either because the prompt was refused or because the site's settings block it. The tuner cannot ask again by itself. Allow the microphone for this site in the browser's site settings, then press "Start tuning" again. The sound is analysed on your device and is not uploaded.

It says "The microphone is being used by another app or tab. Close it and try again."

Another app or tab is holding the microphone. This is common on a phone after a call, and on a computer with a video-call app running in the background. Close the other app or tab, then press "Start tuning" again.

It says "This browser cannot record audio here. Open the page in Chrome, Edge, Firefox or Safari rather than inside another app."

This appears in an amber box in place of the "Start tuning" button when the browser offers no microphone access, as in many in-app browsers; the page checks before you tap. On a page that is not on a secure connection you get "Recording only works on a secure (https) connection." instead. Open the page in a normal browser. The tuning picker and reference tones stay usable meanwhile.

The display stays on "Play a note to begin" while you play.

The tuner is listening but is not getting one clear pitch. Move the microphone closer, mute the other strings and let the string ring. A very quiet signal is ignored, and so are chords, noise and pitches outside 27 to 2,000 Hz. Because the page asks the browser not to boost quiet input, a distant microphone can give a signal that is too weak to read.

How it compares

A clip-on tuner senses the instrument's vibration instead of room sound, so it copes with a noisy room better than any microphone-based tuner, including this one. This tool listens through the microphone, reads one note at a time and shows the nearest note, the cents from it and, for a chosen tuning, the nearest string. It covers fixed presets for guitar, bass, ukulele, mandolin, banjo and violin, with A4 between 430 and 450 Hz. It has no custom tunings, no strobe display and no chord detection. In exchange nothing needs installing, and the sound is analysed in your browser and is not uploaded.