Detect the tempo (beats per minute) of audio files and music tracks.
A BPM Detector reports the tempo of an audio file in beats per minute. You give it a track, the browser decodes it, and the tool looks for the interval at which the music's energy recurs: measure the gap between beats, then convert with 60 / seconds-per-beat. The surprise: a song has no single correct tempo. A groove you count at 90 BPM reads just as well as 180 if you count twice as fast, and the tool has to pick one interpretation. Expect a confident number that disagrees with the tempo on a streaming page, in DJ software, or in your own head.
A concrete input and expected output from the current implementation.
Input
A 16-second click track: one short click every 0.5 seconds (2 clicks per second), nothing else.
Expected output
120 BPM
The click-to-click interval is 0.5 seconds, and 60 / 0.5 = 120, so the estimate is 120 beats per minute. A click train is the cleanest possible input for tempo estimation: every energy peak recurs at exactly that interval, with no competing pattern strong enough to shift the result.
The audio is decoded into a stream of samples and reduced to an energy profile over time; beats show up as recurring peaks. The tool measures the dominant interval between peaks and converts it using BPM = 60 / seconds-per-beat, so a peak every 0.5 seconds reports 120. Which interval counts as dominant is the judgment call: bass emphasis and how strictly the beat recurs both pull the answer.
Everything happens in the browser tab: the file is read, decoded, and analyzed in memory, and nothing is uploaded. That also means support for a given file is whatever the browser's built-in decoders provide - WAV and MP3 decode in the major browsers, while M4A, FLAC, and Ogg depend on the browser. A file that will not open here is not necessarily corrupt.
Both numbers describe the same music: 65 counts the beat at half the rate, 130 at double. The tool reports the periodicity its analysis finds strongest, which is a judgment call rather than a fact about the recording, and how you personally count the beat is a third opinion. Cross-check with a tap-tempo tool and keep the count you can dance to.
No. The file is decoded and analyzed inside the browser tab and is not transmitted, which also means the tool works without a network connection. The practical catch is decoding: WAV and MP3 open in the major browsers, while M4A, FLAC, and Ogg depend on the browser, so a file that will not analyze here may still play fine elsewhere.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Convert between bytes, KB, MB, GB, and TB with precise binary and decimal calculations.
Open, view, and edit CSV files in a spreadsheet-style table with sorting and filtering.
Visualize JSON data as a collapsible tree with syntax highlighting and search.
Generate Code 128, EAN, UPC, and other barcode formats with customizable size and labels.
Convert images to Base64 data URLs and decode Base64 strings back to images.
Generate Apache .htaccess redirect rules for 301, 302, and rewrite configurations.