BPM Counter
Measure a tempo by tapping a button in time with the beat.
BPM & Key Finder
Estimate the tempo and musical key of a recording. The result includes confidence scores so you can judge whether the rhythm or tonal evidence is clear.
Audio and transcripts stay on your device. Processing runs in your browser.
Choose a file
MP3, WAV, M4A, OGG, FLAC. Up to 100 MiB per file (50 MiB on touch devices), 1800 seconds. Decoded audio memory limits also apply.
Settings
Result
Your result will appear here
Add a file, pick your settings, then select Find BPM and key.
Your result will appear here.
TXT uses your edited text. SRT and VTT use the timed segments; edit segment text below for subtitle changes.
No account or daily usage quota. File and device limits protect your browser from running out of memory.
How to use BPM & Key Finder
- Choose a supported recording with audible music.
- Press Find BPM and key. Audio is decoded locally and analyzed in a background worker.
- Read the estimated BPM, key and confidence scores.
- Check the tempo by tapping along with BPM Counter or listening beside a metronome.
What the estimates measure
Tempo estimation measures changes in spectral energy and searches for repeating intervals in an onset envelope. The strongest repetition can correspond to a beat, a subdivision or every other beat.
Key estimation groups spectral energy into pitch classes and compares the profile with major and minor key templates. The tool analyzes up to 120 seconds drawn from the beginning, middle and end of longer recordings. A single answer summarizes those regions rather than tracking key changes.
Confidence needs a listening check
A confidence score describes how strongly the analysis favored its estimate. It is not a calibrated probability of musical correctness. Syncopation, swing, live tempo changes, percussion-only passages and key modulation can weaken or confuse the result.
If a track is reported near 70 BPM but you hear the beat near 140, check the half-time interpretation with BPM Counter. Online Metronome helps compare a steady pulse with the recording.
Before you download
- Results are estimates and are not a substitute for listening or a musician’s analysis.
- Mixed-key music, tuning differences and sparse pitched content can give uncertain key estimates.
- Long recordings are sampled across representative regions; the result does not mark each tempo or key change.
Frequently asked questions
Why is the BPM half or double what I expected?
Rhythms often repeat at several related rates. The algorithm can favor half-time, double-time or a subdivision. Tap along to the beat you want to count.
Can it identify the key of speech?
Speech does not normally provide the stable tonal structure needed for a musical key estimate. Use a music recording with audible pitched instruments.
What do the confidence scores mean?
They summarize the strength and separation of the algorithm’s candidates. They are heuristic scores, not measured probabilities of accuracy.
Does the finder upload my song?
No. Decoding and analysis run locally in the browser. The file is not sent to a recognition service.
Related tools
Often used together with BPM & Key Finder.
Online Metronome
Play a scheduled beat with adjustable tempo, bar length and volume.
MP3 Cutter
Trim MP3 audio with waveform positioning and exact time fields.