Free Online Guitar Tuner & Instrument Tuner_
Chromatic mic tuner with ±1-cent YIN detection · needle + strobe display · auto string detection · pitch history · 18 tunings · tone generator · fullscreen. Free, 100% private — no audio leaves your device. 🎸
A4
440 Hz
INSTRUMENT
GATE
mic off
—
press START and play a note
NEEDLE — CENTS-50 · 0 · +50
STROBE — drift right = sharp · left = flat · frozen = in tune
PITCH HISTORY — last 8 s±50 cents
WAVE
VOLUME
Tap a note to play it continuously — tap again to stop. Follows the A4 reference. Tip: the low E string is E2, the A string A2.
A serious chromatic tuner, free in your browser
This free online guitar tuner listens through your microphone and detects pitch with the YIN algorithm — accurate to about ±1 cent, resolved with parabolic interpolation and median smoothing. Read it three ways: a big analog needle with a green ±5-cent in-tune zone, a professional strobe band that drifts while you're off and freezes when you're perfect, and a scrolling pitch history graph that shows your note settling in real time. Everything runs locally with the Web Audio API — no audio is recorded or uploaded.
Pick one of 18 tunings — guitar standard, drop D, half-step down, DADGAD, open G, open D, 7-string, 12-string, 4- and 5-string bass, ukulele and baritone ukulele, mandolin, 5-string banjo, violin, viola and cello, or full chromatic — and the tuner recognises which string you're playing, highlights it, and checks it off once you hold it in tune. Shift the A4 reference anywhere from 415 to 466 Hz (432/440/442 presets), tap any string for its reference tone, or open the tone generator keyboard to tune by ear. Press F for fullscreen — the wake lock keeps your screen on through a whole tune-up.
FAQ — online guitar & instrument tuner
How does the online guitar tuner work?
Press Start and allow microphone access, then play a single note. The tuner analyses the sound with the Web Audio API and the YIN pitch-detection algorithm — the same family of algorithm used in serious tuner apps — and shows the detected note plus how many cents sharp or flat you are. Tune until the needle sits in the green centre and the strobe stops drifting.
How accurate is this tuner?
YIN with parabolic interpolation resolves pitch to roughly ±1 cent under normal conditions — far finer than the ±5 cents most ears can distinguish. For the last fraction of a cent, watch the strobe band: it drifts right when you're sharp, left when you're flat, and stands still when you're exactly in tune.
What is strobe mode?
A strobe tuner shows pitch error as motion instead of needle position: the striped band scrolls in the direction of your error, at a speed proportional to how far off you are. Even a 1-cent error produces visible slow drift, which makes a strobe the most precise way to tune — it's what professional rack tuners use. When the stripes freeze, you're in tune.
What is automatic string detection?
With an instrument preset selected, the tuner recognises which string you're playing by finding the nearest string in the tuning, highlights it, and measures your error against that string's target. Hold a string in tune for a moment and it gets a ✓ — the progress row shows how many strings are done, so you always know where you are in a full tune-up.
What is standard guitar tuning?
Standard six-string guitar tuning is E2 A2 D3 G3 B3 E4, from the thick low string to the thin high string. The Guitar preset snaps to the nearest of those six strings; choose Chromatic to tune to any note.
Which instruments and tunings are supported?
18 presets: guitar (standard, drop D, half-step down, DADGAD, open G, open D, 7-string, 12-string), bass (4- and 5-string), ukulele and baritone ukulele, mandolin, 5-string banjo, violin, viola, cello, plus a chromatic mode that tunes any note — so it works for almost any instrument that plays a clear sustained pitch.
What does the pitch history graph show?
A scrolling trace of the last several seconds of your pitch, in cents. Watch the note bloom sharp on the attack, settle as it sustains, and see whether a tuning peg is creeping — useful for spotting slipping tuners, intonation habits or new strings that still need stretching.
How do I use the tone generator?
Switch to the TONE tab and tap any note from C2 to B5 — it plays continuously until you tap it again, so you can tune by ear the traditional way. Choose sine, triangle, square or organ waveforms; the organ voice adds harmonics that make low notes easier to hear on small speakers. The generator follows your A4 reference setting.
Can I change the A4 reference pitch?
Yes — it defaults to A4 = 440 Hz but you can set anything from 415 to 466 Hz, with one-tap presets for 432, 440 and 442 Hz. Both the tuner targets and the tone generator follow the reference — useful for orchestras at 442, baroque pitch at 415, or 432 Hz experiments.
Why doesn't the tuner detect my note?
Usually one of three things: the signal is too quiet (play closer to the mic, or lower the GATE slider), background noise is confusing the detector (raise the gate), or the note has decayed into mostly harmonics. Pluck once, moderately hard, and let the note ring — avoid strumming several strings at once, since the tuner tracks one pitch at a time.
Is my audio recorded or uploaded?
No. All pitch detection happens locally in your browser. The microphone stream is analysed in real time and never recorded, stored or sent to any server — you can verify in your browser's network tab that nothing is transmitted.
What are cents?
A cent is 1/100 of a semitone. Most people can't hear errors under about 5 cents, which is why the green in-tune zone is ±5 cents; the strobe lets you chase the last cent if you want it perfect.
How do I tune a 12-string guitar?
Select the 12-string preset. The four lower courses (E A D G) pair a normal string with one an octave higher; B and E courses are unison. Tune the main string of each course first, then its octave pair — chromatic mode confirms the octave strings (E3 A3 D4 G4).
Does it work on my phone?
Yes — any modern mobile browser. Allow microphone access when prompted; on iPhones the page uses a full-page fullscreen fallback since iOS Safari doesn't expose true fullscreen. The wake lock keeps the screen on while you tune.
Is it free?
Completely free, no account, no ads, no time limits. It runs entirely in your browser — one of the free tools at jasperbernaers.com.