What key is this song in?

Finding a song's key: the chromagram, the profiles, and the relative-key trap

Two tracks in clashing keys grind against each other even when the tempos match perfectly — the crowd hears it before it can name it. Key is the second coordinate every song has, and knowing it is the difference between a blend and a collision, between sampling in tune and fighting a semitone all night.

This page reads the key from the audio itself, shows the evidence, and is honest about the one mistake every key detector makes.

§How to find the key of a song

1. Drop the fileAny WAV, MP3, M4A, OGG, or FLAC. Decoding and analysis run on your device — nothing uploads.
2. Read key and CamelotThe big readout is the best-scoring key; the Camelot code next to it is the same answer in DJ coordinates.
3. Check the alternativesThe runner-up chips matter: if the relative major or minor is listed, the two were close — decide by ear.
4. Verify with the droneOpen the Drone check mode, sustain the tonic under the song, and A/B major against relative minor. One will feel resolved.

01From waveform to chromagram

The detector starts with a chromagram: the song is run through an FFT, and every frequency between 55 Hz and 5 kHz is folded onto the twelve pitch classes — every C in every octave lands in one C bucket, every F# in the F# bucket, weighted by energy. Four minutes of stereo audio reduce to twelve numbers: how much of the song lives on each note of the chromatic scale.

02Krumhansl profiles: scoring all twenty-four keys

Those twelve numbers are then correlated against the Krumhansl–Schmuckler key profiles — reference patterns of how strongly each scale degree tends to sound in major and in minor keys. Rotate the profile to each of the twelve tonics, in both modes, and you get twenty-four scores. The best score is the verdict; the gap between first and second place is the confidence.

The Chroma view mode shows exactly this evidence: the twelve bins with note labels, and the top candidates with their scores side by side, so you can see whether the winner won by a street or by a nose.

03The relative-key trap

A minor and C major contain the same seven notes, so their chromagrams are nearly identical — the profiles differ mainly in how much weight sits on the tonic. That makes relative-key confusion the signature failure of every chromagram-based detector, commercial ones included. It is why the alternatives are always shown here rather than hidden.

Your ear settles it faster than any algorithm: the Drone check sustains the candidate tonic under the actual song. Over the right tonic the track sounds anchored; over the relative, it floats.

04Camelot: keys as coordinates

The Camelot system renames every key to a number-letter pair — 8B for C major, 8A for A minor — so harmonic mixing becomes arithmetic: same number blends, ±1 number blends, letter swap at the same number is the relative switch. This page gives you the code for one song; the interactive wheel on songremixer.com is the canonical map for planning the journey between them.

05Where the chromagram loses the plot

Heavily percussive tracks bury the harmonic evidence — a drum-dominant instrumental gives twelve nearly-equal bins and a shrug. Modal and blues material genuinely lives between the major and minor templates. A song that changes key mid-way produces a chromagram of both keys blended, and a master tuned off A = 440 smears energy across neighboring bins. Low confidence on this page is the detector telling you it met one of those — physics, not malfunction.

06One song here, the whole crate in the studio

This page hears one file per drop and forgets it when the tab closes. The studio's BPMandKey analyzes your entire library — every track fingerprinted, key and Camelot code and BPM cached permanently, so your crate becomes sortable by harmonic compatibility instead of by filename. The detection you just watched happen once, done for everything you own, remembered forever.