How to find the key of a song
The key of a song is the home note it resolves to and the scale its melody and chords are built from. Knowing it helps you improvise over a track, transpose it for a singer, or pick songs that mix smoothly.
This tool listens to a song through your microphone or reads an audio file, and reports the most likely key. Analysis happens in your browser, so nothing is uploaded.
How the key detector works
The audio is split into short frames and the strongest spectral peaks are mapped onto the twelve pitch classes, ignoring octave. Adding those up gives a pitch profile: how much of the song sits on C, C sharp, D and so on. The detector first measures whether the recording is slightly sharp or flat of A440, so a mistuned track is still read correctly.
That profile is compared with two published models of how major and minor keys behave, the Krumhansl-Kessler and Temperley profiles, at all twelve transpositions. The best match wins, and the confidence score reflects how clearly it beats the runner-up.
Getting an accurate result
A few habits make a large difference to the reading.
- Give it twenty seconds or more. Longer audio covers more of the harmony.
- Pick a section with chords or a melody. A drum-only intro has no pitch to read.
- When using the microphone, keep the room quiet and play the music at moderate volume.
- Songs that modulate will report the key that dominates the analysed section.
A relative major and minor, such as C major and A minor, share the same notes. When confidence is low, the alternative list usually shows the relative key.
Camelot and Open Key codes
DJs label keys on a wheel of twelve numbers so that compatible tracks are easy to spot. Move one step either way, or switch between the A and B ring, and the two tracks stay harmonically compatible. Both Camelot and Open Key codes are shown for every result.
Measure the tempo of the same track with the BPM Counter, check your instrument with the Tuner, or build chords from the detected key with the Chord Generator.