Detect the tempo (BPM) and musical key of a track automatically. Drop in a file and both appear in the Studio's Tempo & Key tile — analysed on your device, never uploaded.
Open the Audio Studio
Go to the DefyAudio Studio and sign in with your free account.
Add your song
Drop in an MP3, WAV, FLAC, OGG, M4A or AAC file, or a video in MP4, MOV, MKV or WebM.
Read the Tempo & Key tile
Once the file is analysed, the Tempo & Key tile shows the BPM with the key underneath (for example "A minor"), next to the format, duration and loudness.
Act on it
Still in the Studio, shift the pitch by up to 12 semitones to reach another key, or change the speed from 0.5x to 2x to match another tempo.
Automatic BPM
The tempo is estimated from the track's rhythm — no tapping along required.
Major or minor key
The key is read from the track's harmonic content and reported as a note plus major or minor.
Analyse then act
Pitch, speed, trim and conversion are in the same Studio, one tab away.
BPM (beats per minute) is the tempo of a track, and the key is its tonal centre — the two numbers DJs, producers and musicians need to mix, mash up, or play along. DefyAudio detects both as soon as you load a file: the tempo from the pattern of note onsets, and the key by comparing the track's pitch content against major and minor key profiles.
Both readings are taken from the first minute of the track. That is enough for most songs, which hold one tempo and one key; a track that changes tempo or modulates later on will be reported by its opening.
To mix two songs, bring them to the same tempo with the Speed control, which changes tempo without changing pitch. To sing or play along in a more comfortable range, or to make two tracks share a key, use the Pitch control, which shifts by semitones without changing tempo.
The analysis runs locally in your browser through WebAssembly, so the song is never uploaded.
Add the song to DefyAudio's Studio. The tempo is detected automatically and shown in the Tempo & Key tile — no tapping needed.
Yes. The same tile shows the detected key, such as "C major" or "A minor", under the BPM.
The BPM is usually close; on some tracks it may report half or double the real tempo. Key detection works best on tonal music and is less reliable on speech, noise or heavily percussive tracks. Both are read from the first 60 seconds.
Yes, a free DefyAudio account. Nothing is installed and the file stays on your device.
No — analysis runs in your browser, so the file never leaves your device.