Guide

Wrong BPM in your music library: how to find and fix it

If you DJ or build playlists by tempo, you notice it fast: one track shows up at half tempo, another is a few beats off, and plenty have no key at all. That is rarely the fault of whatever app you happen to be using. It comes from data that has drifted into your files over the years.

Where wrong values come from

• Half or double tempo. On fast tracks, an analysis often counts only every second beat, and on slow ones twice as many. That is how drum and bass ends up in hip-hop territory, and the other way round.
• Old values from somewhere else. Many files carry a tempo that some other app or a download store entered at some point. Nobody ever checked whether it was right.
• Keys in several spellings. Sometimes it says “Am”, sometimes “A minor”, sometimes a Camelot value. For sorting, those are three different entries.
• Empty fields. Whatever was never analysed has no value either.

Entering tempo in the Music app

The Music app does not measure tempo itself, but it shows it and lets you change it:

• Select a track, then choose “Get Info…”.
• On the “Details” tab you will find the “bpm” field. Type in the value and confirm with “OK”.
• In the song list, right-click the column headers to show the “bpm” column, then sort by it. Outliers in an album or a playlist stand out quickly that way.

The Music app has no field for the key. If you want to see it there, you need a different tool.

Tempo and key in DJ software

rekordbox, Serato and Traktor analyse tempo and key on their own and keep the results in their own collection. If something looks off, check the beatgrid there and fix half or double tempo directly on the track. Whether a DJ app also writes its values into the file depends on the app and its settings. That is why the file, the Music app and your DJ software sometimes show different values for the same track.

Double-checking by hand

• Tap along to a suspicious track; many DJ apps have a tap button for exactly this.
• Compare outliers with neighbouring tracks in the same genre.
• Settle on one way of writing keys and stick to it.

Where Truffle takes over

Truffle measures tempo and key on the Mac itself, without internet, and suggests the values field by field. Above roughly 130 BPM, the tempo is an approximation you should check by ear. Truffle works with your Apple Music library, local folders and collections from rekordbox, Serato and Traktor, but never writes to a DJ app’s database: cues, beatgrids, crates and sets stay exactly as they are. Nothing is written until you confirm. The app is free to try: analyse 100 tracks, write 20.

Updated: 8 October 2026