Find the key

Unlike tempo (how FAST a track is), key describes which base scale and root note carry the harmony - important for DJs who want to layer two tracks in compatible keys via "harmonic mixing" (e.g. the Camelot wheel), for producers who need to transpose a sample to fit their own song, or for musicians who want to accompany a track by ear.

The estimate uses a 12-class chroma analysis: a fast Fourier transform breaks the frequency spectrum into time windows, each frequency is assigned to one of twelve pitch classes (C, C# D ... B), and the energy per class is summed up. The resulting chroma profile is then compared against the 24 classic major/minor scale profiles by Krumhansl and Schmuckler - the best match yields the estimated key.

As with the BPM tool: the result is an algorithmic ESTIMATE, not an exact musical analysis - for atonal music, pure drum tracks or key changes over the course of a piece, it can come out uncertain. A confidence value shows how clearly the chroma pattern matched a particular key.

Specifications

In 3 steps

1. Drop your music file.
2. Choose the output format (text or JSON).
3. Read the estimated key and confidence.

Limitations: The result is an algorithmic estimate (chroma analysis + Krumhansl-Schmuckler correlation), not an exact musical analysis - for atonal or drum-heavy music it can come out uncertain. Very short clips (under 3 seconds) are refused with a clear message. A key change within the track is not detected, only one overall key across the whole file.

FAQ

Related tools

Find the BPM · Create a spectrogram · Create a waveform image · Reverse audio