How do I find the key of a song?

Drop the file into the tool above. Your browser decodes it, builds a pitch-class profile, and names the closest key, with the runner-up shown whenever the two are genuinely close.

Can it find the BPM of any song?

Any song with a reasonably steady beat, yes, and it shows the half- and double-time reading too, since a beat at 174 also fits 87. Rubato performances and tempo changes are where every tempo detector, this one included, becomes unreliable.

How accurate is a song key finder?

Measured on real records, not only on test tones. On 417 songs across ten genres that the method was not tuned on, its key is exactly right on 49 % and scores 69 out of 100 on the standard MIREX scale, which gives partial credit for a fifth or the relative key; on 200 electronic tracks it scores 59. Records that change key, sit in a mode or barely have a tonal center are where it goes wrong, and the tool says when it is unsure instead of guessing.

Do I have to upload my track?

No. The analysis runs entirely in your browser; this page has no endpoint that could receive audio. Closing the tab removes every trace of the file.

Free tool

Song key & BPM finder

Find the key of a song and its tempo in one pass. Drop in a track and get its key and BPM, and where the answer is genuinely ambiguous, both of the answers rather than a coin flip.

Nothing is uploaded. The file is decoded and analyzed by your own browser; this page has no endpoint to send audio to.

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.

See how stem separation works

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 center at all.

What has been measured, in October 2026, on songs with published annotations that the method was not tuned on: the tempo reading is within 4 % on 67 % of 500 songs across ten genres, and the right tempo is on the page, as the reading or as its half or double, for 85 %. The key reading is exactly right on 49 % of 417 songs and scores 69 out of 100 on the standard MIREX scale, which counts a fifth or the relative key as partly right; on 200 electronic tracks it scores 59. On synthesized material with a known answer, the tempo lands within half a BPM from 90 to 174.

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 labeled 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.
What the compatible keys are for: Under the result the tool lists the relative key and the keys a fifth either side: the neighbors DJs call adjacent on the Camelot wheel. Tracks in these keys share most of their notes, which is why mixing between them, or borrowing a sample across them, tends to work without retuning.
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.

Check a track’s loudness Read about loudness

Common questions

Asked the way people ask it

Short answers; the sections above carry the full reasoning.

How do I find the key of a song?: Drop the file into the tool above. Your browser decodes it, builds a pitch-class profile, and names the closest key, with the runner-up shown whenever the two are genuinely close.
Can it find the BPM of any song?: Any song with a reasonably steady beat, yes, and it shows the half- and double-time reading too, since a beat at 174 also fits 87. Rubato performances and tempo changes are where every tempo detector, this one included, becomes unreliable.
How accurate is a song key finder?: Measured on real records, not only on test tones. On 417 songs across ten genres that the method was not tuned on, its key is exactly right on 49 % and scores 69 out of 100 on the standard MIREX scale, which gives partial credit for a fifth or the relative key; on 200 electronic tracks it scores 59. Records that change key, sit in a mode or barely have a tonal center are where it goes wrong, and the tool says when it is unsure instead of guessing.
Do I have to upload my track?: No. The analysis runs entirely in your browser; this page has no endpoint that could receive audio. Closing the tab removes every trace of the file.