Pitch Detector logo PitchDetector

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Real-Time Pitch Detector for Voice & Instruments

Sing, hum, or play a note and see the exact musical note, octave, frequency in hertz and cent deviation update live. Built on the browser's Web Audio API with an autocorrelation pitch-tracking algorithm — the same family of methods used in professional tuners and vocal-training software.

Start detecting pitch See how it works

How to use it in 3 steps

No settings to learn. If you can press one button, you can use this tool.

  1. Step 1

    Allow microphone

    Press Start Detection and choose Allow in your browser's permission prompt. Nothing is recorded — the audio is analysed and discarded frame by frame.

  2. Step 2

    Sing or play an instrument

    Hold one steady note about 15–30 cm from the mic. One note at a time gives the cleanest reading — chords contain several fundamentals at once.

  3. Step 3

    Watch the pitch update live

    The needle centres when you are in tune. Green means within ±5 cents, amber means close, red means adjust. The graph shows how steady you are holding the note.

Live pitch detector

Works with your voice and with any pitched instrument. Headphones are optional.

Microphone: not connected yet

Tip: press Space to start or stop detection at any time.

Singing? Pick your voice type so the detector locks to the right octave automatically. Playing an instrument? Leave it on Any.

Octave correction: off — showing whatever octave is detected

Pitch tuning meter An animated needle showing how many cents the detected pitch is above or below the nearest note. -50-25 0+25+50

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0.0 Hz

Play or sing a note to begin

♭ Too flat — tune up ✓ In tune ♯ Too sharp — tune down

Current note --
Octave --
Frequency -- Hz
Target frequency -- Hz
Cent deviation --
Sharp / flat --
Signal strength ?
Silent
Tuning accuracy ?
Waiting for a tone
440 Hz

Click a key, or press the keyboard, to hear a reference note

Every key has a shortcut, shown underneath it — Z–M and the row above for the lower octave, Q–I and the row above for the upper. Use headphones so the tuner doesn't pick the note back up.

Live waveform the shape of the sound reaching your mic
Frequency over time how steady your pitch is

Processing happens entirely inside this page. No audio is uploaded, recorded, or shared.

Tips for a rock-solid reading

  • Quiet room. Fans, air conditioning and traffic add low-frequency noise that confuses any pitch tracker.
  • One note at a time. Chords contain multiple fundamentals; the detector reports the strongest one.
  • Hold the note ~2 seconds. Pitch algorithms need several complete wave cycles — low notes need longer windows.
  • Sing "ah" or "oh". Open vowels have a strong fundamental; whispering or breathy tone does not.
  • Use headphones for playback. If speakers play a reference tone, the mic hears it too and may lock onto it.
  • Pluck softly. A hard pick attack is briefly sharp; let the string settle for a second before reading.

How does pitch detection work?

The short version, then the science.

The four stages

  1. Capture. getUserMedia() opens the microphone and the Web Audio API delivers raw samples, typically 44,100 or 48,000 per second.
  2. Window. Samples are collected into short overlapping blocks of about 2,048–4,096 samples (≈45–90 ms). Pitch is assumed to be roughly constant inside a block.
  3. Estimate the period. The block is compared with time-shifted copies of itself. The shift that produces the best match is the period T of the waveform. Frequency is simply f = 1 / T. This is autocorrelation; this page uses a normalised square-difference refinement in the family of the YIN and MPM algorithms, plus parabolic interpolation for sub-sample precision.
  4. Convert to a note. The frequency is mapped onto the equal-tempered scale, then the residual is expressed in cents.

The mathematics

MIDI note number n from frequency f with reference A4:

n = 69 + 12 · log2( f / A4 )

Rounding n gives the nearest note; the note name comes from n mod 12 and the octave from ⌊n / 12⌋ − 1. The target frequency of that note is:

ftarget = A4 · 2(n − 69) / 12

And the deviation in cents is:

cents = 1200 · log2( f / ftarget )

Because the scale is logarithmic, one semitone is always 100 cents and one octave is always 1200 cents, whether you are at 55 Hz or 1,760 Hz — even though the hertz gap between adjacent semitones grows as pitch rises.

Why a tuner sometimes disagrees with your ear

A real instrument does not produce a single sine wave. It produces a harmonic series: a fundamental at f plus overtones near 2f, 3f, 4f and so on. Your brain fuses that series into one perceived pitch — a phenomenon called the missing fundamental, since you still hear the pitch even when the fundamental is filtered out. Pitch trackers must do the same job in software, and two classic failure modes appear:

  • Octave errors. A period of 2T also correlates well, so a weak fundamental can be read one octave low. Sustaining the note and staying close to the mic usually fixes it.
  • Inharmonicity. Stiff strings — especially the low register of a piano and heavy bass strings — have overtones slightly above exact multiples. This is why piano tuners deliberately stretch octaves rather than tune every note to a mathematical target.

Human pitch discrimination is roughly 5–10 cents for sustained mid-register tones for untrained listeners, and can approach 2–3 cents for trained musicians. That is why the ±5-cent green zone on the meter is a sensible definition of "in tune" for practical music-making.

Learn the concepts

Everything below is standard, textbook music acoustics — written plainly.

What is a Pitch Detector?

A pitch detector is a tool that listens to a sound and reports which musical pitch it is — as a note name such as A4, as a frequency such as 440 Hz, and as an error in cents from the nearest note in the scale. A guitar tuner is a pitch detector with a musician-friendly display; a vocal-training app is a pitch detector plotted over time; a studio pitch-correction plug-in is a pitch detector wired to a pitch shifter.

This page is a general-purpose version: it does not assume you are tuning a particular instrument, so it will happily read your singing voice, a violin, a tin whistle, a bowl being struck, or a synthesiser.

What is frequency?

Sound is a pressure wave. Frequency is how many complete cycles of that wave pass a point each second. Double the frequency and you go up exactly one octave; halve it and you go down one octave. A few landmarks:

Reference frequencies in equal temperament with A4 = 440 Hz
NoteFrequencyWhere you meet it
E282.41 HzLowest string of a standard guitar
A2110.00 HzTypical bass-baritone comfortable low note
C4261.63 HzMiddle C on the piano
A4440.00 HzConcert pitch tuning reference (ISO 16)
C5523.25 Hz"Top" of many pop vocal melodies
A5880.00 HzOne octave above concert A
C84186.01 HzHighest key on an 88-key piano

What is a hertz (Hz)?

A hertz is just a way to measure vibrations. One hertz = one vibration per second. So when you see 440 Hz, that means the sound is vibrating 440 times every second. The unit is named after Heinrich Hertz, a physicist who was studying electromagnetic waves back in the 1880s.

Human ears can pick up sounds from roughly 20 Hz to 20,000 Hz, though that upper limit drops as you get older. The interesting part for musicians is that all the notes you'll ever sing or play live in just the lower part of that range. A piano keyboard spans from 27.5 Hz (the lowest A) up to 4,186 Hz (the highest C) — everything above that your ear hears as brightness or texture, not as distinct notes.

Quick note on kHz: "kHz" just means 1,000 Hz. You'll see audio sample rates like 44.1 kHz or 48 kHz — these tell you how many times per second the microphone takes a measurement. It's not the same as the pitch you hear; it's just how much detail the recording captures. (There's a technical limit called the Nyquist theorem that says a 48 kHz recording can capture frequencies up to 24 kHz.)

Difference between pitch and frequency

They are related but not the same thing, and mixing them up causes a lot of confusion.

FrequencyPitch
NatureA physical property of the waveA perceptual judgement made by the listener
Measured inHertz (cycles per second)Note names, scale degrees, cents
Measured byInstruments — oscilloscopes, analysersHuman hearing (and models of it)
ScaleLinear: 100 Hz → 200 Hz is +100 HzLogarithmic: 100 Hz → 200 Hz is +1 octave
Can exist without the other?Yes — ultrasound has frequency but no perceived pitchYes — the missing-fundamental effect gives pitch with no energy at that frequency

Three practical consequences:

  • Loudness slightly colours perceived pitch, so a very loud low note can sound marginally flat even when the meter reads 0 cents.
  • Timbre matters: a bright sawtooth and a dull sine at the same frequency have the same pitch but feel different, and beginners often hear the brighter one as "higher".
  • Equal steps in pitch are equal ratios in frequency. That is why the meter reports cents, which behave the same at every register, instead of hertz.

Supported voices and vocal ranges

The detector works across the full practical singing range. Classical voice types and their conventional ranges:

Typical vocal ranges (individual singers vary widely)
Voice typeRangeApprox. frequency
SopranoC4 – C6262 – 1047 Hz
Mezzo-sopranoA3 – A5220 – 880 Hz
Alto / ContraltoF3 – F5175 – 698 Hz
CountertenorG3 – E5196 – 659 Hz
TenorC3 – C5131 – 523 Hz
BaritoneG2 – G498 – 392 Hz
BassE2 – E482 – 330 Hz

Children's voices typically sit between A3 and F5 before the voice changes. Growled, whispered, screamed or heavily distorted vocals have no stable fundamental, so no tuner can track them reliably — that is a property of the sound, not a limitation of this page.

Who can use this pitch detector?

Singers & vocal students

Check whether you are landing on the note or drifting flat as you get louder. Watch the frequency graph to see vibrato width and stability.

Instrumentalists

Tune guitar, bass, ukulele, violin, cello, mandolin, banjo, harp, flute, sax, trumpet, harmonica, or a hand pan — anything with a sustained pitch.

Music teachers

Project the meter in a lesson so students see intonation instead of only hearing it. Excellent for teaching cents and equal temperament.

Producers & engineers

Identify the key of a sample, verify a synth's tuning, or check that a re-amped guitar take is at concert pitch before editing.

Speech & voice therapy

Track habitual speaking pitch and monitor exercises. Useful for voice feminisation/masculinisation practice and for presentation coaching.

Students & makers

Physics and DSP classes can measure tuning forks, strings and resonant tubes, and compare theory against real measurements.

Common uses

  • Tuning an instrument without a hardware tuner or clip-on device
  • Ear training — sing a note, then check whether you hit it
  • Finding the key or root note of a riff, sample or loop
  • Warm-ups: mapping your comfortable range from lowest to highest note
  • Verifying an alternate tuning such as Drop D, DADGAD or Open G
  • Matching an ensemble tuned to A4 = 442 Hz or a baroque group at 415 Hz
  • Checking a tuning fork, singing bowl, wine glass, or a piece of pipe
  • Teaching cents, octaves, harmonics and equal temperament visually
  • Monitoring speaking pitch for coaching or therapy homework

Worked example

You pluck the low E string on a guitar and the readout shows E2 · 80.9 Hz · −32 cents. The target for E2 is 82.41 Hz, so you are almost a third of a semitone flat. Tighten the tuning peg slowly; the needle sweeps to the right and the accuracy gauge climbs. When it reads E2 · 82.4 Hz · −1 cent in the green zone, stop — one cent is far below the audible threshold and chasing 0.0 will only fight the string's natural settling.

Troubleshooting

Almost every problem is one of these six.

The browser never asks for microphone permission

Permission prompts require a secure context. Make sure the address bar shows https:// (or localhost during development). Also check that the page is not inside an <iframe> without a microphone permission policy, and that no extension is blocking media capture. Try a normal window rather than a private/incognito one.

I clicked "Block" by mistake — how do I undo it?

Click the padlock or tune icon at the left of the address bar, find Microphone, set it to Allow, then reload. On iOS, go to Settings → Safari → Microphone, or Settings → Safari → Advanced → Website Data if the site is remembered as blocked. On Android Chrome: ⋮ → Settings → Site settings → Microphone.

"No microphone found"

Your device has no input device the browser can see. Plug in a headset or USB mic, check the OS sound settings show the device as enabled and not muted, close other apps that may hold exclusive access (some conferencing and DAW software does), then reload the page.

No sound is being detected even though I'm singing

The signal-strength bar tells you what the page hears. If it stays flat: the wrong input is selected in your OS, the input gain is at zero, the mic is physically muted (many headsets have an inline switch), or a hardware mute key is active. Move within 30 cm and sing an open "ah" — laptop mics are often on the far edge of the chassis.

The note flickers between two values

You are sitting exactly between two semitones, or the tone is too quiet for a stable estimate, or several notes are sounding at once. Play a single sustained note, get closer to the mic, and give it two seconds. If it flickers by exactly one octave, the fundamental is weak — try a fuller, more open tone.

The room is too noisy

A warning appears when the background level is high relative to your note. Turn off fans, air conditioning and other music, close windows, and move away from computer fans. Soft furnishings help. If you cannot control the room, use a close-talking headset or clip-on mic so your tone dominates the noise floor.

The readings look wrong by exactly one octave

This is the classic octave error described above. Low, breathy or heavily filtered sounds have little energy at the fundamental, so the tracker may lock onto a harmonic or a sub-multiple. Sing more openly, play with a fuller tone, or move the mic closer to the sound source.

Everything reads slightly sharp or flat

Check the A4 reference slider. If it is set to 442 Hz, every note will read about 8 cents flat compared with a 440 Hz instrument. Press Reset to return to 440 Hz. Also remember that instruments drift with temperature — a guitar taken from a cold car reads flat until it warms up.

Frequently asked questions

Is this pitch detector free to use?

Yes — completely free, no account, no limits, nothing to install. It is a single web page that runs in your browser.

Is my microphone audio uploaded anywhere?

No. Analysis happens locally with the Web Audio API. Audio frames are examined and immediately discarded; nothing is recorded, stored or transmitted.

How accurate is the pitch detection?

With a clean sustained tone in a quiet room, expect roughly 1–3 cents of error — finer than most listeners can hear. Accuracy degrades with background noise, very short notes, heavy vibrato, and at the extremes of the frequency range.

What is a cent in music?

A cent is one hundredth of an equal-tempered semitone, so an octave holds 1200 cents. Because it is a ratio-based unit, one cent means the same musical distance at every pitch. Within about ±5 cents most people call a note in tune.

Can I tune a guitar, violin, ukulele or piano with it?

Yes. Sound one string or key at a time and let it settle. For piano, note that professional tuning also involves deliberate octave stretching because of string inharmonicity, so a mathematical tuner is a guide rather than the whole job.

Why does the detected note keep jumping around?

Weak signal, noisy room, or more than one note sounding. Move closer, silence other sources, and sustain a single note. Breathy or whispered voices lack the stable fundamental a tracker needs.

Does it work on iPhone and Android?

Yes, in modern mobile browsers. The page must be served over HTTPS, and you must tap Start Detection — mobile browsers only unlock audio input after a user gesture.

Why can I change the A4 reference from 440 Hz?

440 Hz is the ISO 16 standard, but many orchestras tune to 442 or 443 Hz for brightness, and historically informed ensembles often use 415 Hz. Setting the reference shifts every target frequency so the meter matches your ensemble.

Ready to check your pitch?

One button, instant feedback, nothing to install.

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