How the key finder works
Every song leans on some notes more than others. The key finder measures how much energy sits on each of the 12 pitch classes, C, C sharp, D and so on, across the song. It then compares that pattern with key profiles, templates of how major and minor keys typically use each note.
The best match becomes the estimate, for example G major or F sharp minor. It is an estimate, and songs that change key or stay ambiguous may need a second opinion from your ears.
The analysis runs on your own device and there is nothing to install. Drop a file, read the key, and use it straight away.
Relative keys and why results can differ
Every major key shares its notes with a minor key, called its relative minor. C major and A minor use the same seven notes. Because of that, a key finder can sometimes report the relative key instead of the one you expected.
| Major key | Relative minor | Shared sharps or flats |
|---|---|---|
| C major | A minor | None |
| G major | E minor | 1 sharp |
| D major | B minor | 2 sharps |
| F major | D minor | 1 flat |
| B flat major | G minor | 2 flats |
| E flat major | C minor | 3 flats |
Who needs to know the key of a song
Knowing the key saves time for:
- DJs doing harmonic mixing, so blends do not clash.
- Producers making remixes and mashups.
- Singers choosing whether to transpose a song.
- Guitarists and pianists learning songs by ear.
- Songwriters sampling a loop into a project.
- Music students checking their ear training.
Tips for getting a reliable result
Songs with clear chords and melodies give the best results. Drum-heavy tracks and noise-based music are harder to read.
If the result is the relative minor or major of what you expected, both share the same notes. Listen to which chord feels like home.
For a cleaner read on a busy mix, split the song with the stem splitter and run the other stem, the chords and melody, through the key finder.
Need the song in a different key? Use the key changer to transpose it up or down in semitones.
Check the result against your instrument. Play the root note of the reported key and hold it under the song. If it sounds like home, especially at the end of a chorus, the key is right.
Limitations
The key finder gives one key for the whole song. Songs that modulate, change key partway through, will get the key that dominates overall. Modes other than major and minor, like Dorian or Mixolydian, are reported as the closest major or minor key. Detuned recordings that sit between standard pitches can also confuse it.
Using the key finder for harmonic mixing and singing
DJs use the key of each track to plan blends that sound musical. Tracks in the same key, or keys that are close on the circle of fifths, mix smoothly. A clash between two distant keys is easy to hear during a long blend.
Singers use the key a different way. Once you know a song is in E major and your voice sits better in D, the key changer can move it down 2 semitones. The key finder gives you the starting point for that decision.
| Situation | What to do with the key |
|---|---|
| Two tracks in the same key | Blend freely |
| Keys one step apart on the circle of fifths | Usually blend well |
| Relative major and minor | Blend well, mood shifts |
| Distant keys | Change one track's key or mix quickly |
| Song too high for your voice | Shift down with the key changer |
Private and free key detection
The analysis runs entirely in your browser. Nothing is uploaded, and there is no account or cost. It works on computers and on iPhone and Android.