Free song key finder

How a key finder works

A song in C major uses mostly the notes C, D, E, F, G, A and B, and it keeps coming home to C. A key finder, or key detector, hears that. It splits the audio into short windows, finds the strongest pitches in each, and adds them into a twelve bar profile, one bar for each note of the scale. This profile is called a chromagram.

Then it compares the profile with the shape of a typical major song and a typical minor song, shifted to each of the twelve notes. The closest of the twenty-four matches is the key. We also estimate how far the recording is tuned from standard pitch, so a song that sits a few cents flat does not smear between two notes, and we give a little weight to the bass note, because songs tend to rest on their tonic.

The templates come from music research: Ibrahim Sha'ath's profiles, tuned on dance music, which build on the probe tone ratings of Krumhansl and Kessler. They work best on songs with clear harmony, chords or a melody. A pure drum loop or a noisy texture has no key to find, and we say so.

The Camelot wheel and harmonic mixing

DJs use a simple map to pick tracks that sound good back to back. The Camelot wheel gives each of the twenty-four keys a number from 1 to 12 and a letter. A is minor, B is major, so 8A is A minor and 8B is C major. Moving one step on the wheel, or switching between A and B on the same number, gives a mix that stays in harmony.

On this page the wheel lights up your song and the keys that mix with it: the same key, one step up for a lift in energy, one step down for a calmer move, and the relative major or minor. We also show the Open Key name, the Traktor way of writing it, so that you can read it either way.

This is the idea behind harmonic mixing. It does not replace your ear, but it makes it much faster to find tracks that will not clash.

Relative keys and songs that sit between two keys

C major and A minor use exactly the same notes. They are relative keys: A minor is the relative minor of C major, and C major is the relative major of A minor. A detector sometimes cannot tell which one the song really lives in, especially when the chords wander between them. We show both, with the relative key next to the result, because a human listener would hesitate too.

If a song changes key in the middle, the result is the key that fits the song as a whole. A track that modulates up a tone for the last chorus will still read as its main key. For a precise map of every section you need a chord detector.

The confidence label tells you how sure we are. High means the notes fit one key much better than any other. Low means two keys are close, or that the audio has few pitched notes.

Singers: find the key, then move it

If you want to sing a song and the chorus is too high, you need two things: the key of the song and the key that fits your voice. Drop the song, read the key, then pick the key you want in the shift box. We tell you how many semitones to move it, up or down by the shortest way, and which Camelot code you land on.

This page does not change the audio. To hear the song in the new key, use any pitch shifter or capo and the shift in semitones that we show. Guitarists can read a plus shift as the fret for a capo, and pianists as the number of keys to move.

Producers: match samples and loops to your key

A loop in the wrong key sounds wrong even at the right tempo. Drop a handful of loops and the table lists the key of each one next to its BPM, so you can pick the ones that fit your project or find the ones that are one step away on the wheel.

If a vocal sample is a semitone off, you can shift it by the number we show. And if your own track has no key written down, the scale of the detected key tells you which notes are safe to play over it.

Tips for a better reading

Use a part of the song with chords or a melody. A long intro of drums and noise holds little harmony. Drop the full song when you can: more music means more evidence.

For a sample, give us at least a few seconds with a held note or a chord. A single short hit is not enough to find a key. A bass line on its own gives the tonic well, but it can be unclear if the key is major or minor.

Whenever the answer matters, press Hear the tonic chord or Hear the scale and play along on a keyboard or a guitar. Your ear is the final judge.

Private by design

The song is decoded and analysed in your browser. It is never uploaded and there is no queue. We only count anonymous usage, that the tool was used, the file type and the length in minutes, never the file or its name. It is free, with no sign-up, and it is a beta, so check the answer by ear with the chord and scale buttons.