How to use it
- Choose the tuning reference: A4 at 440, 442 or 415 Hz.
- Press Start listening and allow microphone access when your browser asks.
- Play or sing one steady note, close to the microphone, in a quiet room.
- Read the note name, octave and frequency. The needle leans left when you are flat and right when you are sharp. The text also says "Flat", "Sharp" or "In tune".
- Turn on Hold and average to smooth a wobbly note, then press Stop when you are done.
Your microphone and privacy
The page asks for the microphone only after you press Start listening. The sound is analysed on your device a few times per second and is never recorded, stored or sent anywhere. The microphone is released when you press Stop, when you switch tabs or hide the page, and when you leave. If you block access, nothing is lost: allow it in your browser site settings and try again.
How the pitch is found
The tool takes a short window of the microphone signal and looks for the repeat length of the wave, using a normalised autocorrelation method. The repeat length in samples, divided into the sample rate, gives the frequency. The frequency is then matched to the nearest note of equal temperament, measured from your chosen A4. The distance to that note is shown in cents.
| Note | Frequency in Hz |
|---|---|
| A2 | 110.00 |
| C4 (middle C) | 261.63 |
| A4 | 440.00 |
| A5 | 880.00 |
Tuning standards
Most pianos and pop recordings use A4 = 440 Hz. Many European orchestras tune to 442 Hz. Baroque ensembles often use 415 Hz, close to a semitone lower. Pick the one that matches the instrument or ensemble you are playing with.
Listening or playing a tone
This tool listens. If you want a tool that plays a reference note for you to match, use the reference pitch player.
Common questions
Why does the reading jump around?
A voice or a string has natural wobble, and background noise or several notes at once confuse any single-note detector. Play one note, get closer to the microphone, and turn on Hold and average.
Can it tune a piano?
It can show you how far a single key is from the nearest note, which is useful to check a piano against a standard pitch. Tuning a piano itself is a skilled job for a technician, because strings are tuned in relation to each other.
Why does it show nothing for some notes?
Very quiet sounds and notes below about 50 Hz or above about 2000 Hz are ignored. Soft notes are skipped so that room noise does not show up as a pitch.
Is my sound saved or uploaded?
No. The audio is analysed in your browser and discarded straight away. The note history on the page is kept only until you close it.
Sources
- Pitch detection algorithm: Overview of autocorrelation methods
- Cent (music): How cents measure pitch distance
- Concert pitch: 440, 442 and 415 Hz tuning standards
- MediaDevices.getUserMedia() on MDN: How browsers ask permission for the microphone