BPM
Free BPM and song key finder
Find the tempo and the key of a song, without uploading it.
Drop in an audio file and get its BPM and its key in a few seconds. The file is decoded and measured by your own browser and goes nowhere else, so it works on unreleased music, on client work, and on a plane.
How it works
- 1 Choose a fileWAV, MP3, M4A, OGG and FLAC usually work, up to 60 MB and fifteen minutes. Your browser opens it the same way it would play it.
- 2 It listens for the beatThe page looks for the moments where new sound arrives, then asks how far you have to slide that pattern along before it lines up with itself again. That distance is one beat.
- 3 It listens for the notesIt adds up how much of each of the twelve notes is in the recording, and compares the result with what major and minor keys usually look like, in all twelve positions.
- 4 Use the answerSend the tempo to the drum pattern generator or the metronome, and the key to the chord progression generator or the scale explorer.
Why you get two tempos
A beat at 140 BPM with the snare on beat three can just as fairly be counted at 70. Neither is wrong, and no program can know which one the musicians had in mind. The big number is the one most people would tap their foot to, and the half and double are shown beside it. If you are matching two tracks, either will line up.
Why the key comes with a relative
Every major key shares its seven notes with a minor key three semitones below it: C major and A minor are the same white keys on a piano. What separates them is which note feels like home, and a recording can be vague about that. So the finder names its best answer and the relative beside it. If a song sounds sad and the answer says major, trust your ears and take the relative.
How sure is it?
The bar under each answer shows how far ahead it was of the next candidate. A steady drum beat gives a clear tempo. Rubato piano, ambient music and live recordings that speed up give a guess. Keys are clearest in music with chords and a bassline, and murkiest in music that is mostly drums, or that changes key halfway.
Questions people ask
Is my file uploaded anywhere?
No. The file is read and analyzed by your own browser. Nothing is sent to a server, which is also why it keeps working if your connection drops after the page has loaded.
How does a song key finder work?
It measures how much energy the recording has at each of the twelve notes, across every octave, and compares that fingerprint with the typical fingerprint of each major and minor key. The closest match wins. It is the same method, from the researchers Krumhansl and Schmuckler, that most key detection software is built on.
How accurate is the BPM?
On music with a steady beat it is normally within one BPM, and most recorded music sits on a whole number, so round it. It can land on half or double the tempo you expected, which is why both are shown.
What can I do with the BPM and the key?
Anything that has to fit with the song: make a drum beat at the same tempo, find chords in the same key, choose a second track to mix into it, or set a metronome to practise along.
Ready for the rest of the song?
The studio has this and everything around it: instruments, recipe blocks, an arranger, and a co-producer that explains every change it makes. Free to start, private until you share.