Category: Converters
BPM Detector
Estimate a song's tempo locally by analyzing its beat
Estimate the tempo, in beats per minute, of a local audio file by analyzing its energy peaks entirely in your browser. See a confidence level and alternative tempo candidates alongside the main estimate.
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Detection is based on energy peaks in the audio and works best on music with a steady, audible beat. Ambient, classical or very quiet recordings may return a low-confidence or half/double-tempo result.
The audio file is decoded, processed and exported in your browser. It is never uploaded.
Everything on this page is processed in your browser. Nothing is uploaded.
What this tool does
This tool decodes your audio file with the Web Audio API, builds an energy envelope from it, picks out onset peaks that likely correspond to beats, and looks at the spacing between them to estimate the most likely tempo. Because the same beat pattern can also read as half or double its true tempo, the tool also lists other tempo candidates it considered. Everything runs on your device — nothing is uploaded or recorded.
How to use it
- Choose an audio file from your device.
- Wait a moment while the tempo analysis runs.
- Review the estimated tempo, its confidence, and any alternative tempo candidates.
Privacy
This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.
Frequently asked questions
- Is my audio file uploaded to detect its tempo?
- No. The file is decoded and analyzed entirely in your browser; it is never sent anywhere or recorded.
- Why did it return half or double the tempo I expected?
- Tempo detection from beat spacing alone cannot always tell a fast beat from a slow one with extra hits in between. Check the listed alternative tempo candidates — the tempo you expect is often among them.
- Why is the confidence low or the result missing?
- Tracks without a clear, steady rhythmic pulse — ambient music, spoken word, or very quiet recordings — give the onset detector little to work with, so the estimate becomes less reliable or unavailable.