Pitch Detector

How This Pitch Detector Works

A pitch detector finds the fundamental frequency of a sound — how many times per second the wave repeats — and names the nearest musical note. This one does it in your browser: it takes about 85 milliseconds of microphone sound at a time, measures the repeat period with the YIN method (de Cheveigné and Kawahara, Journal of the Acoustical Society of America, 2002), and turns the period into a note name, a frequency in hertz (Hz) and an offset in cents. The sound stays on your device. Nothing is recorded or uploaded. Updated 2026-11-04.

Voices and instruments are not pure tones: a sung note or a guitar string also carries harmonics at two, three and four times the main frequency, and the second harmonic is often louder than the note itself. Simple detectors read that harmonic and report the note one octave too high. YIN looks for the longest period that truly repeats, which keeps the octave right, and the page also takes the median of the last few readings so a single click or squeak does not move the display.

Reading the Note, Hz and Cents

The big letter is the nearest note in twelve-tone equal temperament, with the octave number in scientific pitch notation: middle C is C4 and the A above it is A4. Sharps are shown with their flat name as well, so A#4 also reads B♭4.

The meter shows cents. A cent is one hundredth of a semitone, so a reading can be at most 50 cents off before it becomes the next note. Inside ±5 cents the label says in tune; otherwise it says how many cents flat (too low) or sharp (too high). Clarity tells you how cleanly the sound repeats: a steady sung vowel or a plucked string reads high, a breathy or noisy sound reads low, and below that the page shows no note at all instead of a guess.

Note frequencies follow the equal-temperament formula f = A4 × 2^{(n − 69) / 12}, where n is the MIDI note number and A4 is 440 Hz, the concert pitch fixed by the international standard ISO 16. Some orchestras tune to 442 or 443 Hz and early-music groups to 415 Hz; pick your reference above and every note and cent value follows it.

The note frequency chart linked below lists every note from C0 to B8.

What a Phone or Laptop Microphone Can and Cannot Do

The detector reads one note at a time. A chord, two singers, or a song playing in the background mixes several pitches, and no reading of a single frequency can name them all; you will see the strongest one or none. It covers about 40 Hz to 2,100 Hz — from a bass guitar's low E (41.2 Hz) to the top of most voices and of the violin's normal range. Very low notes need a moment to settle because each wave takes longer to repeat, and small phone microphones pick up bass notes weakly, so play the low strings of a bass with some force.

The page turns off the browser's echo cancelling, noise suppression and automatic gain, because those filters can cut a steady note out as "noise". Some phones and in-app browsers apply them anyway. If the level bar moves but no note appears, move closer, sing an open vowel such as "ah", and keep the room quiet. This is a practice tool, not a calibrated laboratory instrument: its accuracy depends on your microphone and your room.

Using It to Sing in Tune or Check an Instrument

1. Tap Start listening and allow the microphone.
2. Sing or play a single long note. Watch the needle: left of centre is flat, right is sharp.
3. Adjust until the label says in tune and the needle sits in the shaded zone.
4. Use the pitch line to see whether your note wobbles, slides in from below, or drifts flat at the end of a breath. A steady note draws a flat line.
5. Tap Hold note to freeze the reading so you can look at it after you stop.

Lowest and highest held notes only count notes kept for a moment, not a brief slide, so they give an honest idea of the notes you can sustain. For a full range check with a voice type, use the vocal range test.