LUFS stands for Loudness Units relative to Full Scale. It is an international standard for measuring audio loudness that closely matches how the human ear actually perceives volume. Unlike peak meters that only measure the absolute loudest electrical signal, LUFS takes human hearing curves into account.
In the past, the "Loudness Wars" dominated mastering. Engineers pushed music to the absolute maximum volume, squashing dynamics just to sound louder than the competition on the radio. Today, streaming platforms like Spotify, Apple Music, and YouTube use LUFS normalization.
If your master is -8 LUFS, the streaming platform will simply turn your track down. You lose dynamic range without gaining any perceived loudness advantage.
When measuring loudness, you'll encounter two primary metrics:
LiveMarks includes a built-in LUFS analyzer specifically designed for A/B testing on Android. When you compare two tracks, LiveMarks can automatically match their LUFS levels so you aren't tricked into thinking a louder mix is a "better" mix.