Press Start microphone, allow access and hold one clean note for about a second. The detector shows the nearest note, measured frequency and how many cents the pitch sits sharp or flat. Audio is analyzed inside this browser: the page does not record or upload it.
This is a free live-input tool, not a file uploader or vocal-range test. Its search range is approximately 65–2,000 Hz; low bass E1 (41.2 Hz), A1 (55 Hz) and 50/60 Hz hum are outside it. A harmonic from an out-of-range source is not a valid reading of its fundamental.
Browser pitch tool · local microphone
Find the note you are playing
Microphone access is requested only after Start; your browser may reuse an existing permission. Audio is analyzed on this device and is not recorded or uploaded.
Use one steady voice or instrument note. Chords and noisy rooms can confuse the reading.
Waiting for a stable note
Reference pitchDefault A4 = 440 Hz
Ready. Press Start microphone, allow access, then hold one note for about a second.
How to use the pitch detector
- Choose a quiet position. Move away from fans, loud speakers and other instruments. Reflections and background notes can make the fundamental less stable.
- Press Start microphone. Your browser may ask for microphone permission unless you already granted it; input selection, when available, is in the browser or operating-system audio settings. On a phone, point the built-in microphone toward the source without covering it.
- Play one sustained note. A voice vowel, guitar string, piano note or other clear monophonic source works better than speech, percussion or a chord.
- Read note, Hz and cents together. The note name is the nearest equal-tempered pitch. Frequency is an estimate of the fundamental, not a guaranteed identification. A negative cents value is flat; a positive value is sharp.
- Stop when finished. Stop or Escape releases this tool’s microphone tracks and clears the readings. Hiding the page or navigating away also cancels capture; a late permission grant is discarded. Press Start again to resume.
If the reading jumps, I wouldn't chase every number. Hold the source steady, bring it closer without clipping the input, and give the confidence bar a moment to settle. The display uses a short rolling median, which reduces isolated outliers after several readings but also delays changes between notes.
How to read note, frequency and cents
| Readout | What it means | How to use it |
|---|---|---|
| Note + octave | The nearest note in twelve-tone equal temperament, using C4 for middle C and sharp names (C♯ equals D♭ here) | Identify the pitch region, such as A4 or E2 |
| Frequency | The estimated fundamental in cycles per second | Compare the measured Hz with the target |
| Cents | The logarithmic distance from the nearest target note | Negative is flat, positive is sharp; zero is centered |
| Input level | RMS level of the digital input frame in dBFS, not acoustic loudness or sound pressure | Move closer if too quiet; move back if the input distorts |
| Confidence | How clearly the current frame supports one repeating pitch period | Treat low-confidence note names as provisional; the percentage is not a calibrated probability of the correct note |
One semitone contains 100 cents, so a reading near +50 is halfway from the displayed note toward the next semitone. Cents are logarithmic: the same musical interval uses the same cents distance at low and high frequencies. The number is still an estimate; don't expect every phone microphone or noisy room to resolve the pitch to laboratory precision.
For the note-to-frequency equations behind the display, see the UNSW explanation of notes, MIDI numbers and cents. A4 uses MIDI 69, C4 uses MIDI 60, and cents = 1200 × log2(measured frequency / target frequency). The In tune label means within ±5 cents of this mathematical target, not a claim about hearing thresholds or professional piano tuning.
When to change the A4 reference
The default is A4 = 440 Hz. Leave it there for ordinary modern tuning checks. Open Reference pitch only when an ensemble, recording, historical practice or supplied brief uses another reference. Changing A4 changes the target-note map; it doesn't change the audio captured by the microphone.
For example, at A4 = 440 Hz the A below middle C is A3 at 220 Hz, and the A immediately above middle C is A4 at 440 Hz. A5, one octave above A4, is 880 Hz. Every octave doubles or halves frequency. Other notes follow the equal-tempered ratio of the twelfth root of two. If you need to create a known reference rather than measure one, use the online tone generator. Keep its output quiet. A second device can supply a reference tone, but turn it off before measuring an instrument so the detector does not follow the reference instead. For a static equal-tempered lookup across octaves, use the musical note frequency chart.
The A4 field accepts 415–466 Hz in 0.1 Hz steps. Invalid values clear the note display until corrected; Reset 440 restores the default. The browser is asked to disable echo cancellation, noise suppression and automatic gain control, but these are preferences, not guarantees about device processing. A rejected or quiet frame clears the previous note rather than showing it as a fresh measurement.
Sources that work well and sources that do not
- Voice: sustain one vowel at a comfortable level. Spoken sentences change pitch too quickly for a stable tuner-style reading.
- Guitar and bass: use a note within 65–2,000 Hz, pluck one string and let the initial attack pass. Use the settled body of the note; overtones and fret noise can dominate the first instant.
- Piano and keyboards: play one note. The sharp attack may jump briefly before the sustained tone settles.
- Wind and bowed instruments: hold one steady note with consistent breath or bow pressure.
- Chords: not supported as chord recognition. Several fundamentals and overtones compete, so the result may jump between partials.
- Drums, clicks and noise: usually unsuitable. A transient or broadband signal does not provide one persistent fundamental period.
The supported display range is deliberately limited to roughly 65–2,000 Hz. That covers common voice and instrument fundamentals while leaving enough samples for useful browser analysis. Frequencies outside the range may appear as silence, a harmonic or an unstable result. For a full view of energy across many simultaneous frequencies, use the audio spectrum analyzer; it answers a different question from this note detector.
How the browser estimates pitch
The page reads short microphone frames through the Web Audio API and applies a YIN-style fundamental-frequency estimate. The original YIN pitch-estimation paper describes a difference function and cumulative mean normalization designed to reduce common autocorrelation errors. Here, a confidence threshold rejects weak or ambiguous frames, and a short median smooths accepted frequencies before note conversion.
The detected frequency is converted to an equal-tempered MIDI-note position relative to the selected A4 reference. The nearest integer identifies the note; the remaining logarithmic distance becomes cents. The algorithm runs in page memory, and the microphone source is connected to an analyzer rather than the audio output, so the page shouldn't play your input back through the speakers.
Browser microphone capture is available only in a secure context and requires explicit permission, as documented for MediaDevices.getUserMedia(). Mobile browsers can also suspend Web Audio until a user action, so the page creates and resumes its audio context inside the Start action, consistent with AudioContext.resume().
Why the pitch reading jumps or stays blank
- Permission blocked: allow microphone access for soundforgepro.com in the browser’s site settings, then press Start again.
- No signal: stop this detector, then open the online microphone test to check the selected input and its level. If that meter moves but the pitch display stays blank, return here and hold one steady note within 65–2,000 Hz. A moving input meter confirms a signal; it does not guarantee a detectable fundamental.
- Signal too quiet: reduce the source-to-microphone distance. Do not boost until the room noise becomes louder than the note.
- Reading jumps by an octave: wait past the attack, play more softly or change microphone position. A strong harmonic can briefly look more periodic than the fundamental.
- Wrong note during a chord: isolate one note. This page is a monophonic pitch detector, not a chord detector or key finder.
- Phone does nothing after Start: reload the HTTPS page, make sure the browser has microphone permission and press Start again from the visible button. Private or embedded browsing modes can apply stricter permission rules.
Where pitch detection fits an editing workflow
Pitch detection is useful before a destructive edit: identify a sustained tone within the supported range or document a note before time/pitch processing. I'd use a spectrum analyzer for 50/60 Hz mains hum; those fundamentals are below this detector’s range. It won't repair the audio, though. For recorded material, inspect the spectrum as well, then make the change in your editor and measure again.
If you're changing pitch or duration in Sound Forge, the time-stretch and pitch-shift guide separates musical transposition from duration changes and explains where artifacts tend to appear. Use the tone generator for a fixed test signal and the spectrum analyzer for broadband peaks; this detector is for one live fundamental.
Privacy and measurement limits
- The detector requests microphone access only after you press Start. Stopping capture does not revoke a saved site permission or stop another tab that uses the same microphone.
- The detector does not save a recording, upload audio or connect the microphone to speaker output. Ordinary site analytics are separate; detector events contain no audio, note or frequency values.
- Stop, Escape, page hide and navigation release this tool’s tracks. A pending request is canceled logically: the browser prompt may remain, but any late stream is stopped rather than analyzed.
- The reading depends on the source, room, microphone, sample rate and browser.
- It is not a calibrated frequency counter, hearing test, vocal-range diagnosis or proof of instrument intonation.
Stopping a media track releases this tool’s use of the source; it does not necessarily switch off hardware shared with another app or tab. A browser-reported muted or ended microphone track stops this session. Use the Audio Tools hub to choose a different measurement.
Online pitch detector FAQ
Does the pitch detector record or upload my voice?
No. The live MediaStream is analyzed in the current browser tab. The page does not create a recording, send audio to a server or play the microphone signal through the output.
What does a negative cents reading mean?
A negative value means the measured pitch is flat relative to the nearest displayed target; a positive value means it is sharp. Zero is centered. One semitone equals 100 cents.
Can it detect guitar, bass, piano and voice?
It can estimate one clear, sustained note within roughly 65–2,000 Hz. Low bass E1 at 41.2 Hz and A1 at 55 Hz are outside the range; their overtones may produce misleading readings. Let sharp attacks settle and play one note at a time.
Can this tool identify chords or a song key?
No. It is a monophonic pitch detector. Chord recognition and key estimation require analysis of several simultaneous or time-varying pitches and are separate tasks.
Why does the detector show the wrong octave?
A strong overtone, noisy attack, very low note or weak fundamental can produce an octave error. Hold one note, wait past the attack and adjust microphone position. Even high confidence can describe the wrong octave; compare with the expected register before trusting it.
Should I change A4 from 440 Hz?
Keep 440 Hz unless the ensemble, recording or delivery brief uses another reference. Changing A4 remaps the target frequencies and cents values; it does not alter the captured sound.