Free tool · runs in your browser
Free BPM and Key Finder for Your Beat
Drop a beat, song or loop to get its tempo (BPM), musical key and Camelot number in a few seconds. The file never leaves your device.
Tempo
BPM
Key
Two AI vocal takes on the same file, sung or rapped, your beat unchanged · from $4.99
How the finder works
Tempo: the finder measures how sharply the sound rises from moment to moment (drum hits and note starts), then looks for the repeat that fits best between 50 and 220 BPM, favouring common tempos around 120. This is the method used by librosa, the open-source audio library many music researchers use.
Key: it adds up how much of each of the 12 notes is heard across the track and compares that against the Krumhansl-Kessler profiles of the 24 major and minor keys, the classic Krumhansl-Schmuckler key-finding method. The best match is the key; when the second-best is nearly as good, the page tells you.
We checked it against librosa on our own demo beats: the key matched on 11 of 12, and the tempo agreed within about 3% or came out as its half-time or double-time.
What to do with the tempo and key
- Writing lyrics: at 90 BPM a bar lasts about 2.7 seconds, at 140 BPM about 1.7. Fewer words per line suit faster beats.
- Choosing a style: trap usually sits at 130 to 160, drill at 138 to 145, boom bap at 85 to 95, reggaeton at 90 to 96. See each genre's usual tempo and keys →
- Adding a vocal: the AI singer or rapper below follows your beat's own tempo and key, so you don't need to type them in.
Add AI vocals to your beat
Frequently asked questions
Is my beat uploaded?
No. The finder reads the file inside your browser and nothing leaves your device. Only if you press "Add AI vocals to this beat" does the generator below upload it, like any file you give it.
How accurate is it?
On steady beats the tempo is usually within a beat per minute. Tempo has a half-time and double-time answer, so a 140 BPM drill beat can read as 70; both are shown. Key detection is harder: songs that change key, use modes or have little harmony can read as the relative or a neighbouring key, and the page says when it's a close call.
Why does another tool give a different key?
Major keys and their relative minors (C major and A minor) share the same notes, and tools weigh bass, melody and chords differently. If two answers are relatives, both are reasonable; play the root note on a keyboard and hear which one feels like home.
What files does it read?
Whatever your browser can decode: MP3, WAV, M4A and FLAC in all modern browsers, OGG in most. It measures the first two and a half minutes.
What is the Camelot number?
The Camelot wheel numbers the 24 keys so DJs can mix tracks that sit well together: same number, or one step either way, or the A/B partner (the relative key).
Is it free?
Yes, with no sign-up and no limit. Adding AI vocals to the beat afterwards is the paid part.