Keygrid

How the BPM is measured. Every beat in the track is located, then a straight line is fit through all of their times. The slope of that line is the tempo, so small timing errors on single beats average out across the whole song. The ± figure is the statistical uncertainty of that fit.

Variable tempo means the beats drift (live drummers, older recordings). The four decimals then describe an average, not a fixed grid.

Key comes from the strength of each of the 12 pitch classes across the song, matched against major and minor key profiles. Relative keys share the same notes, so they are the most common mix-up. Key codes use Open Key notation (d = major, m = minor).

Vocal reverb settings are for ValhallaVintageVerb. PreDelay and Decay are timed from the BPM so the reverb fades out with the beat. Mix is set for the plugin on the vocal track.

Vocal delay times are in milliseconds for any delay plugin. Dotted 1/8 and 1/4 are the most common for vocal echoes and throws.

Beat health checks the beat before you record on it. Peak is the loudest sample. Loudness is integrated LUFS (the streaming standard). Dynamics is the gap between peak and loudness; small numbers mean the beat is squashed. Mono check measures how the left and right sides line up; a negative number means parts of the beat cancel out on mono speakers.

Check it by ear. Press Play with click, then Jump to end. If the click is still locked to the kick at the end of the track, the BPM is right.

Credits. Built with Tauri and the Outfit, Figtree and IBM Plex Mono fonts (SIL Open Font License). Beat tracking follows Ellis (2007); key detection uses the Krumhansl–Kessler and Temperley key profiles; loudness follows ITU-R BS.1770. Designed by Christian Collins and written with the help of Claude by Anthropic. Full credits and license texts: third-party notices.

Feedback. Questions, bugs or ideas? Email keygridapp@gmail.com.

Keygrid is not affiliated with or endorsed by Valhalla DSP, Avid (Pro Tools), Antares (Auto-Tune), Celemony (Melodyne) or Mixed In Key. Product names are trademarks of their owners and are mentioned only to describe compatibility.