Guitar Tuner Online - Tune with Your Microphone
Free chromatic tuner for guitar, bass, and ukulele: microphone pitch detection with a cents needle, adjustable A4 reference, and clickable reference tones for tuning by ear.
Press Start tuner, allow microphone access, and play one string at a time. The tuner shows the detected note, the exact frequency, and a needle marking how many cents you are from perfect pitch — green means within 5 cents. No microphone? Click any string chip to hear its reference tone and tune by ear.
Guitar Tuner Online - Tune with Your Microphone
Free chromatic tuner for guitar, bass, and ukulele: microphone pitch detection with a cents needle, adjustable A4 reference, and clickable reference tones for tuning by ear.
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Press Start tuner and play a string
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Target strings
The string closest to what you play is highlighted automatically. Click a string to play its reference tone through your speakers; click it again to stop.
About this online guitar tuner
This tuner turns your device's microphone into a chromatic instrument tuner that runs entirely in the browser — nothing is uploaded, and no app is installed. It captures raw audio with echo cancellation, noise suppression, and automatic gain control switched off, because those phone-call features distort exactly the steady periodic signal a tuner needs. Each animation frame it analyzes a short window of the waveform with a normalized autocorrelation pitch detector (the McLeod method used in professional tuning apps), applies parabolic interpolation for sub-hertz accuracy, and smooths the last few readings with a median filter so the needle stays steady instead of jittering.
The display is chromatic: it names whatever note you play, from a low B on a baritone guitar up past the highest ukulele string, and shows the offset from perfect pitch in cents. A cent is one hundredth of a semitone; the needle spans 50 cents flat to 50 cents sharp, and turns green inside 5 cents — tighter than most players can hear, and a sensible target for everyday tuning. Pluck near the neck pickup or over the sound hole, let the note ring, and tune slowly up to pitch rather than down to it, which keeps the string from slipping flat at the tuning post.
The instrument presets show the target strings with their exact frequencies: standard guitar E A D G B E from E2 at 82.41 Hz to E4 at 329.63 Hz, four-string bass E A D G from E1 at 41.20 Hz, and reentrant ukulele G C E A, where the fourth string G4 at 392.00 Hz is higher than the C string beside it. The string nearest to your playing is highlighted automatically, so an out-of-tune string is matched to the right target instead of a neighbor. Every target is computed from the A4 reference, which defaults to concert pitch at 440 Hz but can be set anywhere from 400 to 480 Hz — set 432 Hz and low E becomes 80.91 Hz, or 442 Hz to match many European orchestras.
Click any string chip to sound its reference pitch as a pure sine tone. That makes the page a complete fallback tuning fork: with no microphone at all you can tune by ear, listening for the slow beating between the tone and your string and stretching the string until the beats disappear. For the lowest bass strings, whose fundamentals sit below what small laptop microphones capture well, playing the 12th-fret harmonic gives the detector a cleaner, stronger note at double the frequency.
Standard tuning targets
Target frequencies for each preset at the default A4 = 440 Hz reference, and what changes when you move the reference.
| String | Target frequency | Notes |
|---|---|---|
| Guitar low E (E2), A4 = 440 Hz | 82.41 Hz | The lowest string in standard guitar tuning — two octaves below E4. |
| Guitar high E (E4), A4 = 440 Hz | 329.63 Hz | The thinnest guitar string; exactly four times the low E frequency. |
| Guitar low E (E2), A4 = 432 Hz | 80.91 Hz | Every target scales with the reference: 432 ÷ 440 of the concert-pitch value. |
| Ukulele G (G4), A4 = 440 Hz | 392.00 Hz | Reentrant tuning — the fourth string is higher in pitch than the C string next to it. |
| Bass low E (E1), A4 = 440 Hz | 41.20 Hz | One octave below guitar low E; play the 12th-fret harmonic if the mic struggles this low. |
| A string (A2), A4 = 442 Hz | 110.50 Hz | Orchestral reference — some ensembles tune slightly sharp of concert pitch. |
How to tune your guitar with the microphone
- Pick your instrument preset — guitar, bass, or ukulele — and leave the A4 reference at 440 Hz unless you need an alternate concert pitch.
- Press Start tuner and allow microphone access when the browser asks. Get the instrument close to the microphone in a quiet room.
- Play one string at a time and let it ring. The nearest target string is highlighted, the big readout names the detected note, and the needle shows cents flat or sharp.
- Turn the tuning peg slowly until the needle sits in the green zone within 5 cents of zero. If you overshoot, tune down below pitch and come back up.
- Repeat for every string, then re-check the first ones — tightening later strings can pull earlier ones slightly flat. Without a mic, click each string chip and match the reference tone by ear.
Guitar tuner FAQ
How accurate is this tuner?
The pitch detector uses normalized autocorrelation with parabolic interpolation, which resolves pitch to a fraction of a cent on a clean, steady note — well beyond the 5-cent green zone and far tighter than tuning by ear. Real-world accuracy depends on your microphone and background noise, so tune in a quiet room and let each string ring.
What is a cent, and how close do I need to get?
A cent is one hundredth of a semitone, so 100 cents separate E from F. Most listeners cannot hear an error under about 5 to 10 cents in normal playing, which is why the needle turns green within 5 cents. Chasing the last cent is unnecessary — fretting pressure alone bends a string more than that.
Why does the tuner struggle with my low bass strings?
A bass low E fundamental sits at 41.20 Hz, below what many laptop and phone microphones reproduce cleanly, and this detector tracks 60 to 1,400 Hz. Play the 12th-fret harmonic instead — it sounds one octave up at 82.41 Hz, is rich and steady, and must match the same tuning target. Alternatively, click the string chip and tune to the reference tone by ear.
What does changing the A4 reference do?
Every note target is derived from A4 in equal temperament, so moving the reference rescales all strings proportionally. At A4 = 432 Hz the guitar low E target becomes 80.91 Hz instead of 82.41 Hz; at 442 Hz everything shifts slightly sharp. Use it to match a fixed-pitch instrument, an orchestra, or a recording that is not at concert pitch.
Is my microphone audio recorded or uploaded?
No. The audio stream is analyzed frame by frame inside your browser with the Web Audio API and immediately discarded — nothing is stored, transmitted, or kept after you press Stop tuner. That is also why the tuner keeps working with no network connection once the page has loaded.
How do I tune by ear with the reference tones?
Click a string chip to hear its exact pitch as a sine tone, then play your string along with it. When the two are close you hear a slow pulsing beat at the frequency difference; tune until the beating slows and vanishes. Click the chip again to stop the tone. This is the same beat-matching method piano tuners use.