Loudness & LUFS

Loudness is the number a store reads before anyone hears your record. Streaming services measure integrated loudness over the whole file with the ITU-R BS.1770 method and turn each track up or down toward a playback reference: Spotify documents −14 LUFS, and Apple’s Sound Check is commonly reported near −16. A −8 LUFS master is not played louder than a −14 one. It is turned down until it matches, and whatever you crushed to get there stays crushed.

The essays here separate the meters people confuse: integrated versus short-term and momentary loudness, loudness versus crest factor, and the quiet intros and fades that drag the whole-song number down. They also cover the traps that come from comparing against platforms instead of files: streamed references that were already normalized, quiet masters whose noise floor gets lifted, album sequences that need one loudness lane, and vertical video that plays by different rules. Start with why streaming turns loud masters down, then read the meter pieces in order.