Find the key of a song
Drop a song and read its key, its relative major or minor, and its Camelot code.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No account, no watermark
Find the musical key of a song from an audio file, with its relative key and Camelot code. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. Files longer than 15 minutes are not analysed, and after one visit and a short wait the page works offline.
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The key of a song is the note it feels like it is coming home to, plus whether that home is a major or a minor scale. Singers want it to pick a song they can reach, guitarists to choose a capo position, and producers to find a sample that sits with the track. This page works it out from the recording itself.
It measures how much of each of the twelve notes is in the song, across the whole file, and compares that pattern with the 24 major and minor keys. The best match is the answer; the page also names the relative key (the major or minor that shares the same notes) and gives the Camelot code.
A worked example: a song comes out as A minor, Likely. Its relative major is C major, and the Camelot code is 8A. To sing it two semitones lower, the key you want is G minor, which you get by moving the pitch down 2 on Pitch and speed changer.
If it says Unsure, the notes did not point clearly to one key. That is common with drones, drums and bass lines on their own, and songs that change key part-way. Try a stretch of the song that has chords or a melody, cut with Trim audio.
Key, relative key and mode
- The key is the tonic note and a mode. In the major mode the music sounds bright, in the minor mode darker; the notes of C major and A minor are the same, so they are relative keys.
- The parallel key is the other mode on the same tonic, such as A major against A minor. The page can mix these up when the third (the note that makes a chord major or minor) is rare or ambiguous in the song.
Use the key
- To sing or play in a different key, move the pitch by the number of semitones between the keys: from C to D is up 2. Pitch and speed changer does that and keeps the tempo.
- To mix two songs, look for the same or neighbouring Camelot codes.
What can fool it
- Detuned recordings (the page corrects for up to 40 cents either way), music with no harmony, very heavy bass, and sections in different keys all lower its accuracy. In our own test it was exactly right for 7 of 15 recordings, and the relative key for 3 more.
How it works
- Drop the song, or tap to pick it. One file at a time is fastest; several are listed together.
- Press Find the key and wait a few seconds.
- Read the key and the relative key, and check them by playing the note on an instrument.
In your browser, not on a server
Your browser decodes the file to plain samples. music-tempo (MIT), a small JavaScript library, finds the loudness jumps (onsets) and the steady beat they line up with, and gives the tempo. The key comes from our own code: it measures how much of each of the 12 notes is in the song, using a Fourier transform, and compares that with the 24 major and minor key profiles published by Krumhansl and Kessler. All of it runs in a background worker in your tab.
Compared with upload-based tools: Some online analysers upload the song to their servers before they can answer, which matters for a demo, a stem or an unreleased track. Here the file is decoded and analysed on your device and never leaves it.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
What is the difference between a key and a scale?
A scale is the set of notes, such as the notes of A natural minor. A key is that scale together with the note that acts as home, so A minor and C major use the same notes in the same pattern but treat a different note as home.
Why does it say the relative minor when I think it is major?
The two share every note, so the notes alone cannot always settle it. Many pop songs spend as much time on the minor chord as on the major one. The page shows the relative key right under the answer so you can choose the one that fits what you hear.
Can I find the key from the chords I know?
This page reads a recording, not chords. If you know the chords, the key is usually the chord the progression keeps resolving to, often the first or last chord of the song.
Does it work for a song I recorded myself?
Yes, if the recording has the whole song in it. A single note or a drum loop does not give it enough notes to work with and the result is marked Unsure.
How accurate is it?
In our own test on 15 recordings with a known key, it was exactly right on 7, the relative major or minor on 3 more, a fifth away on 2, and wrong or in the other mode on 3. Treat it as a good first guess and check it against your ears or an instrument.
Is the song uploaded anywhere?
No. The key is worked out by code running in this page, so the song stays on your device. After your first visit and a short wait you can turn off your internet connection and it still works.
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