Pitch Detector: Find Notes, Hz and Cents Online

This pitch detector identifies the nearest musical note, octave, frequency in hertz, and cents offset from a live microphone signal. Press Start listening, allow microphone access, then sing or play one sustained note. The clearest reading usually appears just after the initial attack, when the sound has settled.

How to use the pitch detector

1. Choose your A4 reference. Leave it at 440 Hz unless the recording, instrument, or session uses a different tuning standard.
2. Press Start listening. The browser asks for microphone permission only after this action.
3. Play one note and hold it. Watch the note name, octave, frequency, and cents reading after the first transient passes.

Use a dry, isolated input when you can. If a backing track plays through speakers, the microphone hears both the target note and the track, so headphones make the result much easier to read. The detector is built for one dominant pitch at a time, not chords or a full mix.

What the note, octave, Hz, and cents readings mean

The large letter is the nearest note in the chromatic scale. The smaller number is its octave, so A3 and A4 share a note name but sit an octave apart. A4 is the A above middle C; under the default reference it is 440 Hz.

Frequency in hertz counts cycles per second. Doubling a frequency raises the pitch by one octave: 220 Hz is A3, 440 Hz is A4, and 880 Hz is A5 when A4 is set to 440 Hz.

Cents show the distance from the nearest equal-tempered note. One semitone contains 100 cents. A negative value is flat, a positive value is sharp, and a reading near zero is centered. The green zone here covers ±5 cents as a practical visual cue, not a claim that every source must stay inside that range. Vibrato, instrument character, and musical context all matter.

Why the reading jumps

A real sound is almost never a perfect sine wave. It carries a fundamental frequency, overtones, noise and an envelope that keeps changing. The detector has to decide which repeating pattern best represents the pitch, and that decision can shift from frame to frame as the signal changes.

The attack is noisy

The first instant of a plucked string, a piano note or a consonant-heavy vocal often holds more transient energy than stable pitch. Let the note ring for a moment before you trust the display. The same habit pays off when you tune inside a DAW.

Vibrato moves by design

Vibrato moves above and below a center pitch on purpose, so don't chase every number. Watch the overall center and how evenly the movement swings around it. A slow scoop into a note is motion too, and doesn't mean the detector is faulty.

Overtones can trigger an octave error

Some sources produce a strong harmonic that briefly looks more regular than the fundamental, and the detector may then show a note one octave too high or too low. Move closer to the source, cut distortion, play a steadier note and compare the result with the pitch you'd expect from the instrument's range.

Chords do not have one answer

A chord holds several fundamentals at once, and this detector is monophonic: it looks for one dominant repeating pitch. It may hop between chord tones, lock onto a strong harmonic or show nothing stable at all. That's expected, and it won't give you a useful chord analysis.

How reference pitch changes the result

The A4 control sets the tuning reference used to map frequency to note names and cents. At 440 Hz, a measured 440 Hz signal reads as A4 at zero cents. Change the reference to 442 Hz and the physical signal stays the same, but the cents comparison shifts.

Match the reference to the session before you make a tuning decision. Older recordings, orchestral sessions, imported samples and deliberately detuned instruments may not use A4 = 440 Hz. If you don't know the reference, start at 440 and compare several sustained notes instead of forcing one sample to zero.

How the microphone analysis works

The browser requests audio through the MediaDevices microphone interface. That interface requires a secure context and permission from the user. Once access is granted, the page reads time-domain samples through a Web Audio AnalyserNode and looks for a repeating period.

The audio is analyzed locally in the page. This tool does not upload the microphone stream. Stop closes the browser audio context and stops every microphone track opened by the detector.

Using the result in FL Studio

The browser detector answers a measurement question: “Which pitch is this sound closest to right now?” FL Studio has separate tools for checking, correcting and editing pitch, so pick your next step based on the job you need to finish.

Use Tuner to check a live Mixer signal

Load Tuner on the relevant Mixer track when you want the same kind of measurement inside the project. Image-Line describes FL Studio Tuner as a monophonic tuner that displays note name, octave, frequency, and cents offset. Put it after the processing you want to evaluate. Heavy distortion or modulation can make the displayed pitch less stable because the plug-in receives the processed signal.

The practical difference is where the listening happens. This page listens through a browser microphone, while Tuner reads the signal routed through FL Studio. If you're checking a recorded sample or an instrument already in the project, Tuner saves you from sending that audio out through speakers and back into a microphone.

Use Pitcher for real-time correction

A detector does not move the note. If a vocal or monophonic lead needs correction during playback, Pitcher is Image-Line's real-time pitch-correction effect. It can constrain detected input toward allowed notes and supports MIDI control. Read our FL Studio Pitcher guide before setting correction speed aggressively; a faster response is not automatically a more natural result.

Use NewTone for detailed recorded edits

For a recorded vocal or instrument take, NewTone provides pitch and time editing after audio is captured. Its note segments make it possible to inspect transitions and edit selected regions rather than applying one live correction behavior to the whole performance. The NewTone workflow guide covers the editor, while our sample pitch-correction guide helps choose a method for imported audio.

Microphone permission and no-signal fixes

If the page says access was denied, open the site's permission controls in the browser and allow the microphone. macOS and Windows can also block microphone access at the system level, so check both layers. Reloading alone won't override a denied permission.

If access succeeds but no note appears, check the selected input device, input level, and physical connection. Then try these changes:

• hold one louder, cleaner note rather than speaking;
• move the microphone closer without clipping the input;
• turn off speakers or use headphones;
• bypass reverb, chorus, delay, and distortion while identifying the source pitch;
• try a mid-range note if the source is extremely low or high.

Some browsers and embedded web views restrict microphone features. A current desktop browser opened directly on the secure page is the most reliable fallback.

Limits that matter

This detector is a quick identification tool, not a lab-grade frequency counter. Room noise, microphone response, sample rate, signal level, vibrato and harmonic balance all affect the estimate. It also can't tell you whether a pitch is musically right for the key, chord or melody; it reports the nearest note under the selected A4 reference.

To tune an isolated instrument, use sustained notes across its range instead of judging it from one pitch. For vocals, read the movement and the center instead of treating every cent of change as an error. For chords, polyphonic material and full mixes, rely on musical analysis and the project context instead of expecting a single note name.

Pitch detector FAQ

Can it detect a note from a song?

It may identify a dominant tone in a sparse passage, but a full song contains many simultaneous notes and percussion. Isolate the source or solo the track in FL Studio for a meaningful reading.

Does it tune the sound automatically?

No. It measures pitch. Use Pitcher for real-time correction or NewTone for detailed editing of recorded audio.

Why does the same note show different cents values?

The source itself may be moving, especially with vibrato, string decay, breath or an unstable attack. Noise and overtones can also nudge the estimate. Read the settled middle of the note and compare several attempts.

Is 440 Hz always the right reference?

It's the common default, but not every recording or ensemble uses it. Match the A4 setting to the material whenever you know its reference.

Eric Norris Nashville-based FL Studio producer and editor focused on practical workflow, mixer routing, troubleshooting, sampling and native Image-Line tools.