BPM Detector
Play music out loud and let your microphone find the tempo - nothing is recorded or uploaded.
Press listen and play some music
Tips for a Clean Reading
- • Turn the music up - the beat needs to be louder than room noise
- • Works best on music with a clear drum beat (house, techno, hip-hop, pop)
- • Give it 5-10 seconds; the reading stabilizes over time
- • A reading that looks half or double the expected tempo is the same groove - see the half-time note on the tap tempo page
- • Ambient or beatless music has no steady onset pattern to measure - tap it instead
Three Ways to Find a Song's BPM
This page listens through the microphone, which is ideal when the music is playing in the room - a DJ set, vinyl, the radio. If you have the track as a file, the key & BPM analyzer reads the tempo (and musical key) straight from the audio with no microphone involved. And if you would rather trust your own ears, the tap BPM counter measures the tempo from your taps - it works on anything you can hear, even through headphones.
Privacy
The audio stream never leaves your device. The detector converts the microphone input into a loudness envelope - a few dozen numbers per second describing how energy rises and falls - and finds the repeating beat pattern in that envelope. No recording is made, no audio is stored, and nothing is transmitted to any server. Stop listening and the data is gone.
Frequently Asked Questions
- How does the BPM detector work?
- It listens through your microphone, measures the energy of the incoming audio about 47 times per second, and finds the repeating pattern of energy spikes - the drum hits. The spacing of that pattern is the tempo. Everything runs in your browser; no audio is recorded, stored, or sent anywhere.
- Why does it need microphone access?
- The microphone is the only way a web page can hear music playing in the room. The audio stream is analyzed in real time and immediately discarded - the tool keeps only a running loudness curve (a list of numbers), never the sound itself.
- The reading looks double or half the tempo I expected - which is right?
- Both describe the same groove. Genres with half-time drum patterns (dubstep, trap) are often produced at one tempo but felt at half of it. The detector prefers the produced-tempo reading; if it looks off for the genre, halve or double it.
- What if it can't find a beat?
- Turn the volume up, move the device closer to the speaker, and make sure the track has a clear drum pattern. Beatless or rubato music has no steady onset pattern to measure - for those, tap the tempo yourself with the tap BPM counter.
- Is there a BPM detector that works without installing an app?
- Yes - this one. It runs in any modern browser on desktop or mobile using the Web Audio API, with no app, account, or upload. For a file on disk, the key & BPM analyzer reads the tempo directly from the audio file instead.