ImmerGround for iPhone, iPad and Mac
Three ways to find the key
- Song. Drop in an MP3, WAV, AAC or FLAC file, or a whole folder. The finder splits the sound into its notes every tenth of a second, corrects for tuning, adds up how much of each of the twelve notes it heard, and compares that profile with the shape of every major and minor key. It also reads the key section by section, so a song that changes key shows where.
- Mic. Play any music out loud, from a streaming app, a record or a band, and press Start listening. It reads the last thirty seconds every second and a half and shows Locked when the answer holds.
- Chords. Type the progression and it ranks the keys those chords belong to, with each chord as a Roman numeral. Handy for a song you are learning, or when you know the chords but not the key.
Reading the answer
The big name is the key. Next to it are its Camelot code and its Open Key code, the two notations DJ software uses (rekordbox calls the Camelot style Alphanumeric). Under it sit the tempo, the tuning and how clear the reading was. Clear means the winning key beat every other by a wide margin; Fair or Unsure means two keys were close, usually a fifth apart, and your ear should decide.
The relative key is always shown too. A minor and C major share every note, so a song can lean either way, and many professional databases disagree on exactly these pairs. Press play with the reference chord on: the finder holds the key’s home chord quietly under the song, which sounds settled when the key is right.
Every key in three notations
| Minor key | Camelot | Open Key | Relative major | Camelot | Open Key |
|---|---|---|---|---|---|
| G♯ minor | 1A | 6m | B major | 1B | 6d |
| E♭ minor | 2A | 7m | F♯ major | 2B | 7d |
| B♭ minor | 3A | 8m | D♭ major | 3B | 8d |
| F minor | 4A | 9m | A♭ major | 4B | 9d |
| C minor | 5A | 10m | E♭ major | 5B | 10d |
| G minor | 6A | 11m | B♭ major | 6B | 11d |
| D minor | 7A | 12m | F major | 7B | 12d |
| A minor | 8A | 1m | C major | 8B | 1d |
| E minor | 9A | 2m | G major | 9B | 2d |
| B minor | 10A | 3m | D major | 10B | 3d |
| F♯ minor | 11A | 4m | A major | 11B | 4d |
| C♯ minor | 12A | 5m | E major | 12B | 5d |
Mixing in key
Harmonic mixing means playing songs whose keys sit next to each other on the wheel, so the basslines and chords of two tracks do not fight during a blend. From any key, four moves are safe: the same code, one hour clockwise (a fifth up), one hour anticlockwise (a fifth down), and the other ring at the same hour (the relative key). Two more lift the energy on purpose: two hours up is a whole tone higher, seven hours up is a semitone higher. Click any key on the wheel above to see its six moves.
How accurate it is, and how we measured
We ran the finder on 146 recordings whose key is known: 77 classical recordings from Wikimedia Commons and 69 electronic, pop and loop recordings from Freesound and Jamendo, every key labelled by its title or tags, first two minutes of each. It named the exact key on 66% of them and the key or a close neighbour on 93%. On the MIREX scale that key detection research uses (1 for the right key, 0.5 for a fifth away, 0.3 for the relative key, 0.2 for the parallel key) it scores 0.77.
Where it slips is where any key finder slips: songs that change key, songs that sit on one chord for minutes, and minor keys whose home chord is rarely played. No detector reads every song right, including the paid ones, so treat a Fair or Unsure reading as two candidates and let your ear choose.
Put the key to work
The key tells you what mixes; the tempo tells you how fast. The BPM finder taps along, reads a file or listens through the mic for the tempo and a beat grid you can check by ear. For the screen behind the booth, the free live visualizer reacts to whatever you play into it, and in the ImmerGround app the beats drive effects on your own clips and photos live.
Guides on keys and mixing
How to find the BPM of a song: by ear, by tapping, or from the file
Count it with a stopwatch, tap along, drop the file in, or let the mic listen. How detectors work, why 87 and 174 are both right, where your DAW shows tempo, and why some songs have no single BPM.
Mixed In Key alternatives: free and cheaper ways to find every key
What Mixed In Key does for its price, eight alternatives from DJ software you may own to free desktop and browser tools, what the one public accuracy test found, and which to pick.
The Camelot wheel explained: every key, every move, and when to break the rules
The circle of fifths with numbers on it. Every key in three notations, the moves that mix and the ones that lift the energy, how DJ software shows keys, and where the rules break.
Questions
Is this key finder free, and does my song get uploaded?
It is free with no account and no limit on songs. Files are decoded and analysed inside your browser, and the microphone is read the same way; nothing is uploaded or recorded.
How accurate is it?
On 146 recordings with a known key (77 classical recordings and 69 electronic, pop and loop recordings), it named the exact key 66% of the time, and the key or its closest neighbour (a fifth away, the relative or the parallel key) 93% of the time. That is a weighted MIREX score of 0.77. Songs that change key, or sit between two keys, are where any key finder slips: check the key timeline and play the reference chord to decide by ear.
Why does it say A minor when I think the song is in C major?
A minor and C major use exactly the same seven notes, so they are the easiest pair to mix up, for software and for people. The finder always shows the other one next to it. The home note decides: the chord a song rests on at the end of a section, and the note the bass keeps returning to.
Can I find the key of a song on Spotify, Apple Music or YouTube?
Yes: switch to Mic, press Start listening and play the song out loud near your device. A web page cannot read another app's audio directly, but the microphone hears it. It gives a first reading after about eight seconds and settles as it keeps listening.
What are Camelot and Open Key?
Two ways DJs write keys so that mixing rules become simple arithmetic. The Camelot wheel numbers the keys 1 to 12 like a clock, A for minor and B for major (A minor is 8A, C major is 8B). Open Key does the same with m and d (A minor is 1m, C major is 1d). Same number, one step either way, or the other letter at the same number: those mix without clashing.
Can it find the key from chords instead of audio?
Yes. Switch to Chords and type the progression, such as Am F C G or Cm7 Fm7 Bb7. It ranks the keys the chords fit, shows each chord as a Roman numeral in that key, and weighs the first and last chords most, because songs usually start or end at home.
What does the tuning line mean?
Most music is tuned to A = 440 Hz. Older records, turntables running slightly fast or slow, and tracks tuned to 432 Hz sit between the notes. The finder measures that offset in cents (a hundredth of a semitone) and corrects for it before it reads the key, so a detuned record still reads right.
Which files can I drop in, and how many?
MP3, WAV, AAC (M4A) and FLAC work in every current browser; OGG works in Chrome and Firefox but not Safari. Drop up to 60 songs at once and they are analysed one after another, then download the list as a CSV. The first twelve minutes of a longer file are analysed.