Online pitch detector

By Daniel Breyer, physicist and one half of Acado, Berlin. He studied theoretical quantum physics, published in Physical Review A, and has made club music as Acado for twenty years.

How to use the pitch detector

Tap the button, allow the microphone when the browser asks, and hold one note for three seconds: a hum or an open “aah” for a voice, one string or one key for an instrument, left to ring. Or choose a file, or drop it on the box. Tap Listen again for the next note; the readings of this visit stay in a short list under the result and are gone when you close the page. There is no pitch detector app to install: the page runs in the browser of a current phone or laptop. If the browser blocked the microphone, allow it in the site settings behind the icon in the address bar and tap again. Without one, the example shows a full reading.

The result reads top to bottom. The note and octave: A4 is 440 Hz, middle C is C4 at 261.63 Hz, C3 the C an octave below. The frequency in Hz: how many times a second the waveform repeats. The cents: a hundred make a semitone, so “30 cents flat” is almost a third of the way down to the next note; under 3 cents off, it says dead on. Stability is how long the pitch held within 25 cents and how far it wandered there: a scoop into the note, an 808's click and its glide don't count. Confidence is how much of the sound agrees on the note and how cleanly the waveform repeats; below 50 %, play the note longer, louder and on its own. The curve shows the pitch over time, ±100 cents around the note.

Vocal pitch detector: what note am I singing?

As a voice pitch detector or vocal note detector: hum, or sing an “aah” at a comfortable volume, straight rather than with vibrato, and hold it through the three seconds: the reading takes the steady stretch, not the slide into it. To watch your voice move while you sing, What note am I singing? reads it live and keeps the last steady note when you stop; the vocal range test finds your lowest and highest notes. For your speaking pitch, hold a vowel at the height you talk at; running speech glides too much to give one note. Adult speaking voices sit at about 90 to 155 Hz for men and 165 to 255 Hz for women (Baken and Orlikoff, Clinical Measurement of Speech and Voice, 2000, after Fitch and Holbrook, 1970). A trained singer's vibrato swings half a semitone to a semitone up and down, five to seven times a second (Sundberg, The Science of the Singing Voice, 1987): the stability line then says the note wandered, and the note named sits near the middle of the swing. For your ear, guess the note before you read it, or sing back a played note in the pitch matching game; the perfect pitch test asks you to name notes without a reference.

Why a pitch detector jumps or shows the wrong octave

A time-domain pitch detector, like this one, looks for the time after which the waveform repeats; one over that time is the frequency. A sound that repeats every period also repeats every two, and a sound whose second harmonic is louder than its note repeats almost as well after half a period: the reader then names the note an octave too high. Deep notes are where it slips most: a phone speaker plays little of a low 808 or a bass's low E, mostly their overtones. A jumping number has plainer causes: a breathy start, a slide, vibrato, room noise, a second instrument, a microphone too close to something loud. Hold one note, alone, and step back from a loud source.

This one reads every sound from 60 Hz to 2 kHz and, when the note sits below G3 (196 Hz) or the first pass hears too little, once more slowly, down to 31 Hz (B0, the lowest string of a five-string bass). Then it compares how alike the waveform is after one period, two periods and half a period, and moves the note by an octave when the waveform says so. Moments that jump by an octave or two inside a held note are folded back onto it. The note it reports is the one the sound repeats at, the one a tuner, a sampler or a singer needs.

Pitch detector from an audio file, MP3 or video

Choose or drop a WAV, MP3 or M4A, or anything else your browser plays: a voice memo, a one-shot, a held note, a stem with a single line. All channels are mixed to one, and six seconds are read from where the sound starts, in this tab. Trim a longer recording to the note you want first. For a video, save its sound as an audio file, or play it next to the microphone. A full mix or a chord has no single pitch: the reading names the note held longest and says when there was more than one. For a sample's root note over its whole length, use the root note finder; for every note of a sung line, Hum to MIDI.

How often it gets the octave wrong

Measured on 65 generated tones from B0 to C7 (a sine, a saw, an 808 clean and through a phone speaker, a sung vowel, and a tone whose second harmonic is ten times louder than its note) and on 93 real hummed notes from 12 takes, each against the note that was hummed.

Right means within half a semitone; on the right tones the reading was off by 0.7 cents in the middle. A hum wanders, so a hummed note counts within one semitone, and since the singer picks the octave, a hummed note is an octave error when it lands an octave away from the rest of its take. Of the hums, 73 read right, 13 as another note (the hum slid, or the reader missed) and 7 were too short to read. Measured on 28 October 2026 by a script in our repository; the page's own check fails when these numbers and the script disagree.

Guitar, bass, violin, piano: one note at a time

Play one string or one key and let it ring; the reading comes from the steady part after the attack. A plucked string starts a few cents sharp and settles as it rings, which is why a reading taken at the pluck looks sharp. To tune, the tuner is quicker: a live needle while you turn the peg, and a tap on a string plays its note. The open strings in equal temperament, from A4 = 440 Hz:

A bass's low E at 41.2 Hz sits below 60 Hz, where the slow pass reads it; a phone microphone hears more of its overtones than of the note, and the waveform still repeats at 41.2 Hz. A piano is tuned stretched: its strings' overtones run slightly sharp, so tuners set the top notes sharp and the bottom notes flat of equal temperament, by up to about 30 cents at the ends of the keyboard (the Railsback curve, 1938). A few cents off on a tuned piano is the stretch, not a fault. Its range covers most of the keyboard, not all: the two lowest keys, A0 (27.5 Hz) and A♯0 (29.14 Hz), sit below B0, and the top octave above C7 (2093 Hz) up to C8 (4186 Hz) is above what it reads.

Trumpet, clarinet, saxophone: written and sounding notes

A pitch detector names the note that sounds, concert pitch. A B♭ trumpet or clarinet sounds a whole tone below what it reads: written C5 sounds B♭4, 466.16 Hz. An alto saxophone sounds a major sixth lower than written, a tenor saxophone a major ninth, a horn in F a fifth. Add the interval back for the written note, or use the trumpet, clarinet or saxophone tuner, which name the notes as you read them.

Hz, notes and cents: the numbers behind the reading

Equal temperament splits the octave into twelve equal steps: each semitone multiplies the frequency by the twelfth root of 2, 1.05946. From A4 = 440 Hz, the note n semitones away is 440 × 2^n/12: A3 is 220 Hz, A5 880 Hz, middle C, nine semitones down, 261.63 Hz. The distance between two frequencies in cents is 1200 × log₂(f₂ / f₁). So 445 Hz is A4 plus 19.6 cents, and 300 Hz is D4 (293.66 Hz) plus 37 cents. The note frequency chart lists every note.

How many cents off is out of tune? It depends on how you hear it. One after the other, near 1 kHz, about 0.2 % (some 3.5 cents) can be told apart (Moore, An Introduction to the Psychology of Hearing, 2012). Together in a band, 10 cents at A4 beat 2.5 times a second, the wobble that sounds out of tune. A sung note with vibrato is heard at the centre of its swing, so judge that centre, not each moment.

One cent is a change of 0.058 % in frequency: 0.25 Hz at A4, 0.03 Hz at A1 (55 Hz). The same precision takes more waveform in the bass, which is why low notes need the longer read.

Pitch, frequency, tone and note

Frequency is a measurement, in cycles a second. Pitch is how high a sound seems; for a sound with a clear period it follows the fundamental, even when the fundamental itself is missing. A telephone line drops everything under 300 Hz, and a man's voice at 110 Hz still sounds at 110 Hz, because its harmonics that pass the line, 330, 440 and 550 Hz (the third, fourth and fifth), still repeat together every 9.1 ms. A tone is a sound with a pitch, a note is that pitch's name: a tone detector, a music note detector and a pitch detector are the same tool.

How pitch detection works

There are two ways in. A spectrum (the FFT) splits the sound into its frequencies; a note's harmonics stand at 1, 2, 3, 4 times its fundamental, and the tallest peak is often not the first. A spectrum is also blurred by short windows: its steps are one over the length analysed, 25 Hz for 40 ms, while the semitone from F1 to F♯1 is 2.6 Hz wide. The other way, in the time domain, looks for the lag after which the waveform matches itself: autocorrelation, and its refinements YIN (de Cheveigné and Kawahara, 2002), the McLeod pitch method (McLeod and Wyvill, 2005) and probabilistic YIN (Mauch and Dixon, 2014).

This page uses YIN on 40 ms windows every 10 ms, a second pass at half speed for the sub-bass, and the octave check above. Like every reader of one voice, it follows one dominant pitch: a chord, two singers or a song's full mix have none to give.

A = 440, 442 or 432 Hz

The chips under the button set the A the names and cents are measured from. 440 Hz is the standard (agreed in London in 1939, ISO 16 since 1955, revised 1975). Many orchestras tune to 442 or 443. 432 Hz is 8 Hz, 1.8 %, or 31.8 cents below 440: switch to 432 and a sample at 432 Hz reads as an A dead on instead of 32 cents flat. Every interval stays the same; the whole scale moves down a third of a semitone. Where 432 comes from, and what the few studies on it measured, is on the 432 Hz tuner. To hear both, play 432 Hz and then 440 Hz on the tone generator; on two phones at once they beat 8 times a second.

What it doesn't read

• High-pitched sounds and noises. As a high pitch sound detector it stops at about 2 kHz: it reads from B0 (30.9 Hz) to about C7 (2093 Hz), the range its benchmark tested. A smoke alarm's chirp, usually around 3 kHz, a charger's whine or a dog whistle sit above it; for those, a spectrum analyser app shows the frequency.
• Chords and finished songs, and their key. One note at a time. A recorded song plays many notes at once, so its key needs a reader made for chords (Mixed In Key and Rekordbox analyse a full mix, Tunebat lists released songs), and this site doesn't have one. What it can do: hum the song's tune into the singing key finder, or give the key finder a file with one voice in it, a stem or a one-note sample, and the key comes from that line.
• Tempo. Pitch is how high, tempo how fast: for BPM, the BPM counter.
• Whether it sounds good. It reads pitch. It doesn't judge a voice or a performance.

Questions

Is a pitch detector the same as a tuner?

Both read pitch. A tuner shows it live, as a needle, for turning a peg until it centres. This page takes one note and tells you more about it: the octave checked, how steady, how sure, the curve. For tuning, the tuner; for naming a sound, here.

Online mic test: does the pitch detector hear my microphone?

Roughly, yes: hold a steady note, and a reading means the microphone hears you. “No steady note” means it heard too little; come closer, sing or play louder, and close other tabs that use the microphone. The tool lifts a quiet phone microphone on its own.

Does Google have a pitch detector?

Google added a tuner to its search in October 2021 (search “google tuner”), and its Hum to Search, from October 2020, names a song from a hum, not the note. Neither gives Hz, an octave check or a reading from a file.

Which octave does my DAW call this?

This page names middle C C4, MIDI note 60, the scientific way. Ableton Live, Logic, Cubase and Bitwig call the same key C3, FL Studio C5. The FL Studio 808 page and its siblings name the note the DAW's way.

Then make something of it

The note goes into Brumm as the first note of a melody, inside a club track with a beat and a bass. The note travels inside the link itself, no account, no upload. Hum a whole line there, and it becomes an instrument.