Online Tuner — Free Chromatic Tuner
This is a free online tuner that listens through your microphone and shows the note you are playing, its exact frequency, and how many cents sharp or flat you are. It is fully chromatic, so it works with guitar, violin, bass, ukulele, voice — any instrument, any tuning.
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Your browser will ask for microphone access when you press Start.
Tuning a specific instrument?
This chromatic tuner works for anything. For a tuner that already knows your strings — with nearest-string snapping, alternate tunings, and reference tones — pick your instrument:
What is a chromatic tuner?
A chromatic tuner detects the pitch of any note you play and shows how far it sits from the nearest of the twelve notes in the octave, measured in cents — hundredths of a semitone. Unlike a guitar-only tuner locked to six target pitches, a chromatic tuner works for every instrument and every tuning. On this page, green means you are within ±5 cents: in tune by any practical standard.
How to tune a guitar with this online tuner
- Press Start tuning and allow microphone access when the browser asks.
- Pluck the low E string on its own and let it ring.
- Watch the display: you want E2 with the needle centered. Below zero means flat — tighten the string; above zero means sharp — loosen it.
- Repeat for the remaining strings: A2, D3, G3, B3, E4.
One habit worth stealing from guitar techs: if a string is sharp, tune it down below the target and come back up. Strings hold tune better when the last motion is upward.
Other standard tunings
- Violin: G3, D4, A4, E5
- Bass guitar: E1, A1, D2, G2
- Ukulele: G4, C4, E4, A4 (reentrant — the G is higher than the C)
Because the tuner is chromatic, it recognizes all of these automatically — just play a string and match the note name and octave. If you want the exact pitch of every note in hertz, see the note frequency chart.
Why microphone tuning works — and where your audio goes
The tuner analyzes the raw waveform from your microphone with an autocorrelation algorithm: it finds the period at which the signal best repeats, refines it with parabolic interpolation, and smooths the last few readings so the needle stays steady. It measures what you actually played — no flattery, no guessing. When the signal is too quiet or too messy to call honestly, the display dims instead of showing a made-up note.
Everything runs locally in your browser via the Web Audio API. Your audio is never recorded, stored, or uploaded — it never leaves your device.
Once you are in tune, the other half of sounding good is timing: keep the online metronome in the next tab, or use the tap BPM counter to find the tempo of the song you are learning.
Frequently asked questions
Why won’t the tuner hear my instrument?
First check that your browser has microphone permission for this site — click the mic or padlock icon in the address bar. Make sure no other app (a call, a DAW, another tuner tab) is holding the microphone. Then play a single sustained note, reasonably close to the mic: the tuner deliberately ignores quiet, unclear signals instead of guessing, so a faint or very short note will leave the display dimmed.
Is 440 Hz or 432 Hz correct?
A4 = 440 Hz is the international standard (ISO 16) and what virtually all modern recordings, fixed-pitch instruments, and other musicians use — if in doubt, use 440. Some orchestras tune slightly higher (441–443 Hz), and 432 Hz is an alternative reference some players simply prefer the sound of. There is no scientific basis for 432 Hz being special, but this tuner supports 432–446 Hz so you can match whatever the music around you uses.
How accurate is this tuner?
On a clear, sustained note the detection is typically accurate to within a couple of cents — comfortably tighter than the ±5 cents most musicians treat as in tune, which is when the display turns green. It measures the waveform directly using autocorrelation with parabolic interpolation and smooths the last five readings with a median filter, so single noisy frames don’t jerk the needle. Real-world accuracy also depends on your microphone and background noise.
Can I tune a violin, ukulele, or bass with it?
Yes. This is a chromatic tuner, so it recognizes any of the twelve notes in any octave — violin (G3 D4 A4 E5), ukulele (G4 C4 E4 A4), bass (E1 A1 D2 G2), cello, mandolin, banjo, wind instruments, or voice. One tip for bass: the low E1 at about 41 Hz is hard for small laptop mics to pick up, so play firmly close to the mic or tune the 12th-fret harmonic an octave up.
Does my audio get uploaded?
No. All pitch detection runs locally in your browser using the Web Audio API. Nothing is recorded, stored, or transmitted — the audio never leaves your device, and the page works offline once loaded.
Want this tuner in your pocket?
Get the iOS app — the screen turns green when you are in tune. Free, no clutter.