BPM & KEY

Manual

1. BPM & KEY analyzes an audio file to automatically detect its tempo (BPM) and musical key — useful for tagging tracks or checking a file before loading it into a DAW. To use it, drop an audio file onto the drop zone or click to choose one. Once analysis finishes, the BPM, key, and a confidence score appear in the Readout.

2. The analysis runs entirely in your browser, in a background Web Worker. The file is never uploaded anywhere.

3. Accuracy notes: BPM detection can mistake a tempo for its half or double (for example, reading a 128 BPM track as 64 or 256). When the detected value falls outside the typical range for most tracks (roughly 70–160 BPM), a 'possible half/double tempo' note is shown. Key detection can be less accurate for sparse or slow ballads, or tracks with complex harmony.

4. FAQ: Q. The result doesn't match the track. A. Check the half/double tempo note first. Beyond that, some tracks change tempo or modulate key partway through, and the analysis produces a single value based on the track's overall tendency, so it may not match every section. Q. Which file formats are supported? A. Any common audio format your browser can decode — WAV, MP3, FLAC, AAC, OGG, and more.