Free tool
BPM & key finder
One tool doing both jobs — a BPM checker and a song key finder. Drop in a track and get its tempo and key, and where the answer is genuinely ambiguous, both of the answers rather than a coin flip.
Drop a track, or choose one. It is read on this device and never sent anywhere.
Beyond the numbers
Need the parts, not just the tempo?
This page answers the question first. One soft next step, after the result.
A remix or a mashup starts from the stems as much as from the key and the tempo. Euphona’s stem separation splits a track into vocals, drums, bass and the rest at full sample rate, and the engine reads key and tempo automatically on every upload — so the numbers this page gives you arrive with the parts they describe.
Accuracy
How good is it, honestly
What has been measured, what has not, and the cases where it will be wrong.
Tempo detection is close to solved for music with a steady beat and unreliable for music without one. Key detection is harder: every method, including this one, is wrong on a meaningful share of real music, because plenty of records change key, sit in a mode that's neither major nor minor, or barely have a tonal centre at all.
What has been measured: on synthesised material with a known answer, the tempo reading lands within half a BPM from 90 to 174, and the key reading finds the right one for plain major and minor progressions. What has not been measured is accuracy on real records, which needs a licensed, labelled corpus — so we are not going to quote you a percentage we have not earned.
Instead the tool tells you when it's unsure, and shows the pitch-class chart the key was read from so you can check the reasoning rather than trust the label.
- Why two tempos
- A beat at 174 also fits 87 — every other onset. Both are defensible and drum & bass is routinely labelled either way, so the tool shows the alternative instead of hiding a choice it made for you.
- Why two keys
- C major and A minor contain exactly the same seven notes. Only emphasis separates them, which is something a chroma method reads weakly — so when those two are close, you get both.
- Where it will fail
- Rubato performances, tempo changes, key changes, modal and atonal music, and heavily percussive tracks with little pitched content. In most of those it will say it is uncertain, which is the correct answer.
- How it works
- Tempo from the autocorrelation of a spectral-flux onset envelope; key by correlating a chromagram against published key profiles. Both are textbook methods, and neither shares anything with the Euphona Engine.