Pitch Detector Online
Sing, play, or whistle — the note, its frequency in Hz, and the offset in cents show up in real time. Or drop in an MP3 and get the pitch curve of the whole file.
- ±1 ¢ on clean sustained tones
- 35 Hz – 2 kHz range
- 0 bytes uploaded
- Free, no signup
- Offline after first load
Everything runs in your browser with the Web Audio API. There is no server listening on the other end — which is also why it stays free and works on a plane.
How to use it
- Press "Start listening" and allow microphone access when the browser asks. The permission applies to this page only.
- Play or sing one note. The big letter is the nearest note; the needle shows how many cents sharp or flat you are. Inside ±5 ¢ it turns cyan.
- Tune, log, export. Pick an instrument preset to see string targets, let held notes collect in the session log, and export it as CSV when you're done.
What's in the box
Live mic detection
Autocorrelation with sub-sample refinement, readings only above 88% clarity — it never guesses. Read it on a needle, or switch to the pro-style strobe display where the band freezes when you're in tune.
MP3 / file analysis
Drop in MP3, WAV, OGG, M4A or FLAC. Get a pitch-over-time chart, median pitch, range, and a CSV with one row per 50 ms.
Reference tones
Sine, triangle, square or saw from 20 Hz to 2 kHz, with click-free ramps. Tap any string pill to hear its exact target.
A4 calibration
Detune the whole scale from 415 to 466 Hz. Baroque 415, standard 440, orchestra 442 — cents recompute instantly.
Own your data
Session log and file analysis export to CSV; the pitch chart exports to PNG. Your measurements are yours to keep.
Share a setup
A4, preset, and tone settings encode into the URL. Send the link and the other person opens the tool configured exactly like yours.
What it can and can't measure
Honesty over magic: this is a monophonic detector. One note at a time — voice, guitar string, violin, whistle, flute, a tuning fork. It will not transcribe a chord, separate a full mix, or pull vocals out of a song. On file analysis, busy sections simply produce gaps in the track rather than wrong notes.
Phone and laptop microphones roll off below ~80 Hz, so a bass low E (41 Hz) may read from its overtones — usually still correct, occasionally an octave up. The device report inside the tool shows what your hardware reported and whether the browser kept any audio processing switched on.
FAQ
Is this pitch detector free?
Yes. No account, no paywall, no trial. The whole tool is JavaScript running in your browser, so there's no server cost to pass on to you.
Does my audio get uploaded anywhere?
No. Mic input and audio files are processed with the Web Audio API on your own device. Nothing is recorded, stored, or sent over the network — the page even works with your connection switched off.
How accurate is the reading?
Better than ±1 cent on a clean, sustained tone above roughly 80 Hz. Heavy vibrato, chords, or a noisy room reduce that. When the detector isn't confident, it shows a dash instead of guessing.
Can I detect the pitch of an MP3 or WAV file?
Yes — the File tab. The file is decoded locally and you get a pitch-over-time chart, summary stats, and CSV/PNG export. Files up to 6 minutes are analyzed.
Why does it sometimes show a dash instead of a note?
A note is reported only when autocorrelation clarity passes 88%. Below that — silence, noise, several notes at once — any reading would be a guess, so it shows nothing rather than faking one.
Does it work on a phone, and offline?
Yes. It's built mobile-first and installs as a PWA: add it to your home screen and it opens full-screen and runs with no connection after the first load.