Written by Vincent Sullivan | Last updated: June 2026
What This Site Is
OnlinePitchDetector.com is a free, browser-based tool that detects the fundamental frequency of a sound captured through your microphone in real time — displaying the frequency in Hz, the nearest musical note name, and the cents deviation from equal temperament — and explains what each part of that result means with technical precision.
The site is built and maintained by Vincent Sullivan, audio signal processing educator. Every tool, every explanation, and every piece of educational content on this site is Vincent’s direct work. There are no advertisers, no sponsored recommendations, and no third-party contributors shaping what appears here.
Most browser-based pitch detection tools show you a note name. OnlinePitchDetector.com shows you a note name, a frequency in Hz, and how many cents sharp or flat you are relative to equal temperament — because for anyone doing serious intonation work, the note name alone is not enough.
Why This Site Exists
The gap this site fills is precise: most available browser pitch detectors either show only a musical note name without the underlying Hz value and cents deviation, or they show technical data without explaining what it means or documenting how the detection algorithm works and where it fails.
For a musician checking instrument intonation, a cents deviation figure is essential — knowing you are playing “approximately A4” tells you less than knowing you are 22 cents flat of A4. For a developer building a Web Audio API application that uses pitch detection, knowing that the YIN algorithm can produce octave errors under certain conditions is essential for building a reliable user experience. For a student learning about acoustic pitch, understanding the relationship between Hz frequency and the equal temperament scale is foundational.
OnlinePitchDetector.com was built to serve all three of these audiences with the same tool — one that detects F0 accurately using YIN autocorrelation, displays all three output values (Hz, note name, cents), and documents every significant technical decision behind the detection pipeline. For the complete technical documentation, see the How It Works page.
What This Site Provides
The Online Pitch Detector A browser-based real-time pitch detection tool. The tool captures live microphone audio, applies YIN autocorrelation-based fundamental frequency detection, maps the detected frequency to the nearest musical note in equal temperament (A4 = 440 Hz), calculates the cents deviation, and displays all three values in real time. All audio processing is local — nothing is transmitted. See the Data Security page for the full technical explanation.
Educational Content Articles and explainers covering the YIN algorithm, FFT analysis, equal temperament mathematics, the cents system, ISO pitch standards, intonation science, and the practical application of pitch detection for musicians, developers, and students. All content is written to be technically accurate and genuinely useful — not introductory padding.
Accuracy and Limitations Documentation Every result and accuracy claim on this site includes an honest account of what the detection produces and where it does not. Octave errors, noise floor limitations, OS audio processing interference, and microphone frequency response roll-off at low frequencies are all documented explicitly. The FAQ covers the most common questions about result interpretation.
Who This Site Is For
Musicians checking intonation Whether you are tuning an instrument, checking vocal pitch accuracy, verifying the intonation of a phrase, or practising interval accuracy, the pitch detector gives you Hz, note name, and cents deviation — the three numbers that define where your pitch actually is.
String players, wind players, and singers Instruments and voices require active intonation management. A real-time pitch detector with precise cents display is a practical reference tool for practise and warm-up sessions.
Web Audio API developers OnlinePitchDetector.com provides a documented reference implementation of YIN-based pitch detection in a browser environment, including accuracy figures, algorithm configuration, and known failure modes — directly applicable to building Web Audio API applications.
Music technology students and educators The tool and its documentation make the relationship between acoustic frequency, the YIN algorithm, equal temperament mathematics, and the cents system tangible and interactive for students learning audio signal processing or music acoustics.
Recording engineers and producers Checking the intonation of recorded performances, identifying pitch drift in vocal takes, and verifying tuning consistency across a session are all tasks where a precise, documented pitch reference tool is useful.
Accuracy and Transparency
Vincent Sullivan does not publish accuracy figures, algorithm descriptions, or frequency references without traceable sources. All technical content is cross-referenced against the YIN algorithm paper, the W3C Web Audio API specification, and ISO 16. Limitations are documented on every relevant page — including the Contact page, which is always the right place to report an error.
Get in Touch
contact@onlinepitchdetector.com All questions, corrections, and data requests are handled personally by Vincent Sullivan.
OnlinePitchDetector.com is an independent site with no advertising, no sponsors, and no third-party contributors. All content is written by Vincent Sullivan. Last updated: June 2026.