Key & BPM Finder

It reads the two numbers that describe a track's musical identity at once: the key it is written in, and how fast it runs in beats per minute. One upload, both answers — plus the Camelot code, the relative key and the half-time and double-time tempos.

The key is about which notes a song uses and where it comes to rest — C Major, A Minor and so on. The BPM is about time: how many beats fit into a minute. Two songs can share a key and feel nothing alike because one is twice as fast, and two songs at the same BPM can clash badly if their keys fight.

A transition needs both to line up. Matching BPM makes the beats sit on top of each other; matching keys stops the melodies from clashing while the two records overlap. That combination is what people mean by harmonic mixing, and it is why every DJ library stores a key and a tempo for each track.

Every key gets a number from 1 to 12 and a letter — A for minor, B for major. Safe moves are staying on the same code, stepping one number up or down, or switching letter while keeping the number. So from 8A you can go to 8A, 7A, 9A or 8B. Bigger jumps are possible but you have to want the tension.

Analyse both here, then open the one you want to move in the Audio Studio. Transpose it in semitones until its key matches — each semitone is one step on the wheel — and set the speed to the ratio between the two tempos. Because the studio treats the two controls separately, fixing the tempo will not knock the key back out.

On a turntable, yes — pushing the platter faster raises everything with it. KeyPitch time-stretches instead, so speed and key move independently: you can take a track from 120 to 128 BPM and it stays in the same key, or transpose it two semitones while it keeps its original tempo.

Tempo is the easier of the two: on anything with a steady beat it lands within a fraction of a BPM. Key is an interpretation, so it is right most of the time on clearly tonal music and less certain on tracks that modulate or on heavily percussive material — which is why the runner-up key is listed under the result.

Two disagreements are common and both are shown to you. For the key, the runner-up is usually the relative one — C Major against A Minor — since they share the same seven notes. For the tempo, the half-time and double-time values sit right under the reading, so if the track feels twice as fast as the number, take the double. Your ear settles it.

The key tells a singer whether a song sits in their range, and by how many semitones to move it if it does not. The tempo tells a musician what to set the metronome to, and how far to slow a passage down to learn it. Singing teachers use both to prepare a practice track for each student.

Not directly from a link — this page analyses a file you already have. If the video is yours, or you have downloaded it legitimately, drop the MP4 in and it works exactly like an audio file. For changing the key or the speed of a video while it plays on YouTube, the free KeyPitch Chrome extension does that in real time.

Because the file only has to be decoded once, so the whole thing takes barely longer than either measurement alone. If you are labelling a crate of tracks for a set, or filing a folder of backing tracks, reading both in one pass saves a lot of time. Dedicated pages exist for each if you only need one.

MP3, WAV, M4A and MP4 files up to 50 MB and 10 minutes work, and the tool is completely free with no account needed. Your file never leaves your computer: the analysis runs inside your browser, so nothing is uploaded to a server.