Pitch Detector & Instrument Tuner
Detect the pitch of any note from your microphone and see the nearest musical note and how many cents sharp or flat you are. Runs entirely in your browser.
Pure browser JavaScript — uses getUserMedia and autocorrelation on Web Audio time-domain data.
How to use this tool
- Click Start tuner and allow microphone access.
- Play or sing a single steady note near the microphone.
- Read the detected note, frequency, and how many cents sharp/flat you are.
Detect the pitch of any note from your microphone and see the nearest musical note and how many cents sharp or flat you are. Runs entirely in your browser.
How it works
The Pitch Detector analyses audio from your microphone in real time, applying an autocorrelation algorithm to identify the fundamental frequency of the incoming sound. It then maps that frequency to the nearest musical note on the equal-temperament scale and shows how many cents (hundredths of a semitone) above or below in tune you are.
This makes it function as a chromatic instrument tuner. Pluck a guitar string, blow a wind instrument, or sing a note and the display will show you the note name (for example A4), the reference frequency (440 Hz), and your deviation in cents. Being within plus or minus 5 cents is generally considered in tune for most instruments.
Everything runs in your browser with no upload. The microphone must be close enough to the instrument for reliable detection. Background noise can confuse the detector, so use it in a quiet environment or hold the instrument close to your device's microphone.
Worked example
Tune a guitar string
- Open the tool and grant microphone permission.
- Pluck the low E string (target: E2, 82.4 Hz).
- Read the detected note and cents deviation on screen.
- Tighten or loosen the tuning peg until the cents indicator reads near zero.
- Repeat for each remaining string.
All six guitar strings tuned to within a few cents of their target pitches.
Common mistakes to avoid
- Playing in a noisy room, which causes the detector to latch onto background sounds rather than the instrument.
- Expecting chord or polyphonic detection -- this tool only works reliably on single sustained notes.
- Not waiting for the note to stabilize before reading the cents value -- plucked strings take a moment to settle into a clear fundamental frequency.
Key terms
- Cent
- A unit of musical pitch equal to one hundredth of a semitone. 100 cents equals one semitone; 1200 cents equals one octave.
- Fundamental frequency
- The lowest and usually loudest frequency component of a musical note, perceived as the note's pitch.
- Equal temperament
- A tuning system where the octave is divided into 12 equal semitones, used as the standard for most modern Western instruments.
Frequently asked questions
- How is the pitch found?
- An autocorrelation algorithm runs on the raw time-domain waveform from the AnalyserNode to estimate the fundamental period, which is converted to a frequency and the nearest equal-tempered note (A4 = 440 Hz).
- Why does it say no note sometimes?
- If the signal is too quiet or noisy the detector returns no estimate. Play a clearer, sustained tone closer to the mic.