BPM and key finder

What BPM is

BPM is beats per minute. Sonata measures it from the audio. A tempo written in the file is used only to choose between that measurement and half or double of it.

The detector searches from 60 to 200 BPM and reports a tempo from 75 up to, but not including, 185. When no beat can be found, the analysis keeps a 120 BPM placeholder with no confidence. This page does not show that placeholder as a tempo.

What a key is

A key is the tonic and whether the track is major or minor. Camelot writes that as a number and a letter. 8A is A minor. 8B is C major. A is minor, B is major. The number is the position on the wheel. 8A has its own page, and so does every other code this page reports. Compare two codes on the Camelot key checker, or see them on the Camelot wheel.

How sure the reading is

Sonata gives a key only when a seven-note scale stands out. When it does not, the page says no key was read.

A confidence of 0.5 or more is the line the rest of the app treats as sure enough to mix on. Below that, the key is marked uncertain. A beat grid below 0.35 is marked unclear, and Sonata would not beatmatch it. Both lines were set for the mixer. The key line was tuned on synthesized tracks in a known key.

There is no published accuracy percentage for commercial music, so none is stated here. A matching Camelot code is a shortlist. Hear the tracks before you rely on the mix.

Which pairs are in key

Same code, one step on the wheel, or the relative major or minor is In key. Everything else is a key clash, including the +2 energy boost.

The key used for a pair is the one Sonata would use in a set: a key from the file when the tags name one, otherwise the audio reading. A track with no key is left out. Sonata does not call that a clash.

The Camelot key checker answers the same question for codes you already know.

Common questions

Do my tracks leave this device?

No. Decoding and analysis run in this browser. Your tracks stay on this device. They are never uploaded.

Which files can I add?

MP3, WAV, AIFF, FLAC, M4A, AAC, OGG and Opus, the same types the set planner accepts.

Can I check several tracks?

Yes. Each one is read in turn, then every pair that has a key is marked In key or key clash.

How accurate is the reading?

Sonata gives a key only when a seven-note scale stands out, and it marks a key uncertain below a confidence of 0.5. That line was tuned on synthesized tracks in a known key. There is no published accuracy percentage for commercial music. A tempo is the measured one. When no beat is found, this page says so instead of showing a placeholder. Hear the tracks before you rely on the mix.

Why might this differ from another program?

Different programs weight the audio differently, and a key in the tags can differ from the audio. This page says which one it is using.

What happens if I continue into Sonata?

The same files can be heard as a set. The first mix is free, up to 10 tracks.