Song Key Finder & BPM Finder

How to find the key of a song

1. Choose an audio file of the song from your device.
2. Wait a few seconds while the page decodes the audio and measures which notes are strongest across the track.
3. Read the detected key and its Camelot code, the runner-up keys, and the tempo. Then check the result by ear: play the tonic note along with the chorus and it should sound like home.

How the key finder works

The tool splits the audio into short overlapping windows and measures how much energy falls on each of the twelve pitch classes (C, C#, D and so on), folding every octave together. That twelve-number “chroma” profile is compared with the Krumhansl–Kessler key profiles, a standard model from music psychology of how strongly each note belongs to each of the 24 major and minor keys. The key whose profile matches best wins.

Because relative keys share the same notes, A minor and C major produce very similar profiles. When the top two results are relatives, both are good candidates: they share a Camelot number (8A and 8B) and mix together smoothly either way.

When to double-check the result

• Key changes. Many pop songs move up a step for the last chorus. The tool reports the key that dominates the clip, so trim to the section you plan to use if it matters.
• Modal songs. Tracks in Dorian or Mixolydian often come out as a neighboring major or minor key.
• Drum-heavy or distorted mixes. Percussion and distortion spread energy across all notes, which flattens the profile. Results marked low confidence deserve a check by ear.
• Detuned recordings. Older records and some live takes sit between keys; the result may land a semitone away.

Prefer to work it out yourself? Follow our guide to finding the key of a song by ear. Once you know both songs’ keys, the Camelot wheel shows which pairs blend, the key transposer shows where a pitch shift would take one of them, and the compatibility checker scores the pair with tempo included.

Finding the BPM

The tempo estimate looks for repeating attacks such as kick and snare hits and measures the gap between them. It works best on music with a steady beat. If the number looks half or double what you hear, use Tap BPM to count along, and read about half time vs double time.

Frequently asked questions

How accurate is the key finder?

On songs that stay in one major or minor key, the detected key is usually right or one step away: most often the relative major or minor (A minor instead of C major) or the fifth (G instead of C). That is why the result lists runner-ups. Songs with key changes, modal harmony, heavy distortion or mostly drums are harder. Confirm by ear before you build a mashup on it.

Is my audio uploaded?

No. The file is decoded and analyzed by your browser on this device. Nothing is sent to Mashup Charts or stored, and the analysis works offline once the page has loaded.

Which files work?

Any audio format your browser can play, which usually means MP3, WAV, M4A/AAC, OGG and FLAC. The tool analyzes up to the first four minutes of the file.

Why is the BPM half or double what I expected?

Tempo detection finds a repeating pulse, and many songs can be counted at two levels: a 70 BPM ballad and a 140 BPM trap beat can be the same groove. The result shows the half and double values; tap along in the Tap BPM tool to choose the one that matches how you count it.