BPM & Key Finder – Detect Tempo and Key From an Audio File

How do I analyse my own audio file?

Choose an audio file up to 80 MB. Your browser must be able to decode its format; a filename extension alone does not guarantee compatibility. Analysis starts after selection and processes the audio in the browser. If decoding fails, try a compatibly exported version. Renaming an extension does not change the codec or make an unsupported file decodable.

How is the BPM estimate calculated?

The tempo analyser searches the decoded audio for regular timing and estimates beats per minute. BPM describes tempo rather than a bar count. Ambiguous accents can suggest half-time or double-time readings. If a passage feels like 80 BPM but the result says 160 BPM, compare both counting levels with the audible pulse and your intended application.

Which part of the recording is used for key detection?

Key analysis summarises pitch classes from the first audio channel. It uses up to 180 consecutive blocks of 4,096 samples from the file's beginning: approximately 15 seconds at 48 kHz. A long drum introduction, one chord or an opening unlike the main section can influence the estimate. Shorter files provide fewer complete blocks for analysis.

What do the two candidates and confidence value mean?

Pitch classes are compared with major and minor key profiles. The finder displays the two best-matching candidates and derives confidence from their score gap. The percentage is not a probability that the key is correct. Compare close candidates against melody, bass and resolution points on an instrument. Without a useful tonal distribution, a key result may be unavailable.

How should I check the result before using it?

Compare the BPM estimate with a metronome or Tap BPM measurement in a stable passage. Then test both key candidates against melody and bass. A plausible tempo does not confirm the key: these are separate estimates. The tool changes neither speed nor pitch. Transfer the values to your music software and continue checking against the actual material.

Can I enter a song title instead of a file?

No. Choose your own audio file. The tool does not search a music catalogue by song title, artist name or other text query.

Does high confidence guarantee the correct key?

No. It reflects the leading profiles' score gap, not a probability. Listen carefully when harmony is ambiguous, modulates or fits the profiles poorly.

Why will my audio file not open?

It may exceed 80 MB or use an unsupported audio format. Export a compatible version; renaming the extension does not change codec compatibility.

Can the finder transpose or change the speed of the audio?

No. It estimates tempo and key without editing the recording. Use appropriate audio software to change speed or pitch.