Online guitar tuner
Tune your acoustic or electric guitar with your computer or phone microphone. Pick a tuning, play a string and bring the needle to the centre — the display turns red when the string is in tune.
Sound is analysed on this page and never leaves your browser.
How to tune your guitar online
- Tap “Start tuner” and allow microphone access when your browser asks.
- Choose your tuning — standard E A D G B E is selected by default.
- Play one open string at a time and let it ring. Auto mode finds the nearest string for you.
- If the needle sits left of centre the string is flat: tighten it. Right of centre it is sharp: loosen it.
- Stop when the display flashes red and stays there, then move on to the next string.
- Play a chord at the end and retune any string that drifted while you adjusted the others.
Standard tuning: E A D G B E
From the thickest string to the thinnest, standard tuning is E2 (82.4 Hz), A2 (110 Hz), D3 (146.8 Hz), G3 (196 Hz), B3 (246.9 Hz) and E4 (329.6 Hz). Almost every chord chart, tab and lesson assumes it, so it is the right place to start.
A popular way to remember it: Eddie Ate Dynamite, Good Bye Eddie. Each string is a perfect fourth above the one before, except G to B, which is a major third — that is why the B string is the one that most often sounds “off” in chords.
Alternate tunings in this tuner
Change the tuning menu and the tuner targets the new notes. Each tuning has its own page with chord shapes and songs that use it.
- Drop D (D A D G B E) — heavier riffs and one-finger power chords.
- Half step down (E♭ A♭ D♭ G♭ B♭ E♭) — the sound of Hendrix, SRV and many rock bands, and easier bends.
- DADGAD — open, ringing chords for folk and Celtic music.
- Open G, open D, open E and open C — slide guitar and fingerstyle.
- Drop C, full step down and 7-string standard for metal and lower voices.
How accurate is an online tuner?
This tuner uses autocorrelation pitch detection with interpolation, the same algorithm as the FRET app, so it resolves pitch to well under a cent on a clean signal. In practice your microphone, the room and how hard you pick matter more than the maths: a quiet room and a firm, single note give the steadiest reading.
Everything happens inside this page. The sound from your microphone is analysed in your browser and never uploaded or recorded.
Tuning by ear with reference tones
No microphone, or tuning in a noisy room? Tap any string button below the display to hear a plucked reference note, then match your string to it. When the two notes are close you will hear a slow “wobble”; turn the peg until the wobble disappears.
You can also set the A4 reference between 432 and 446 Hz to match a piano, an older recording or a band that tunes slightly sharp.
Tips for a more stable tuning
Tune up to the note. If a string is sharp, loosen it below the note and come back up. The string holds better because the slack in the gear is taken up.
Mute the other strings. Sympathetic vibrations confuse any tuner. Rest your picking hand lightly on the strings you are not tuning.
Stretch new strings. Fresh strings keep going flat for a day or two. Pull each one gently away from the fretboard and retune a few times.
Check the 12th fret. If an open string is in tune but the 12th-fret note is sharp or flat, the intonation needs adjusting — a job for a strobe tuner.
Guitar tuner questions
Is this guitar tuner really free?
Yes. It runs in your browser with no account, no download and no ads. The FRET iPhone app adds a strobe tuner and more, but this page stays free.
Does it work for acoustic and electric guitar?
Yes. Play an acoustic near the microphone. For an electric, play unplugged near the mic or plug your amp in and let the mic hear the speaker.
Why does the note jump around?
Low notes and harmonics can confuse any tuner for a split second. Pick a single string firmly, mute the others and let the note ring for a moment.
Does it work on iPhone and Android?
Yes, in Safari, Chrome and other modern browsers. On iPhone, tap Start first — browsers only allow audio after a tap — and allow microphone access.
Is my microphone audio sent anywhere?
No. Pitch detection happens on this page. Nothing is uploaded, stored or recorded.
What is the difference between this and a strobe tuner?
A needle tuner like this one is quick and perfect for everyday tuning. A strobe tuner shows tiny differences (a tenth of a cent) for setting intonation — it is in the FRET app.