BPM Detector

How autocorrelation-based BPM detection works

BPM (Beats Per Minute) measures musical tempo, how many beats occur per minute. Automatic detection in this tool uses energy autocorrelation: audio is converted to mono, downsampled to ~4 kHz (efficient and sufficient for beat capture), and the autocorrelation of the energy envelope is computed to find signal periodicity. The autocorrelation peak with highest energy within the 50–220 BPM range determines the main BPM. The confidence score measures the consistency of that peak. For music with variable tempo or complex rhythms, the manual Tap Tempo is more reliable. No data is sent to the server.

Analyze automatically or use Tap Tempo

1. Upload your audio file and click Analyze BPM.
2. Check the result: the detected beats are drawn over the waveform and the metronome clicks on them. If the click does not land with the music, use ½ or ×2, or pick one of the other hypotheses.
3. If confidence is low, use Tap Tempo: tap the button (or press T) in time with the music.

Use this tool on your site

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Sources and references for this tool

These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.

• Autocorrelation, Signal ProcessingWikipedia, Mathematical definition of autocorrelation, core technique in the BPM detection algorithm.
• Beat Detection AlgorithmsRice University, Overview of beat detection algorithms using energy envelope analysis.
• Web Audio API, AnalyserNodeMDN Web Docs, Web Audio analysis node, reference for spectrum and energy analysis.

Frequently asked questions

Where to go next