The units
- LUFS (Loudness Units relative to Full Scale): a measure of perceived loudness according to the ITU-R BS.1770 standard, with a weighting curve that mimics the ear.
- Integrated: average over the whole track.
- Short-term (3 s window) and Momentary (400 ms): useful for comparing sections.
- LRA (loudness range): how much the loudness varies between quiet and loud parts.
- True peak (dBTP): the real peak after signal reconstruction, which can exceed the sampled peak.
Platform normalization
Streaming platforms turn tracks down (and in some cases up) toward a reference level. Spotify gives as its target −14 LUFS integrated and recommends a true peak below −1 dBTP; for masters louder than −14 LUFS it recommends staying below −2 dBTP, because lossy encoding can generate distortion. Other common references: Apple Music around −16 LUFS, European broadcast (EBU R128) −23 LUFS.
What this means in practice
- A master at −8 LUFS on Spotify is turned down by about 6 dB: the extra loudness does not translate into volume, but the loss of dynamics remains.
- Many genres (pop, rap, trap, EDM) still stay on masters between −9 and −6 LUFS as an aesthetic choice: compression is part of the sound.
- Choose the level for the genre and for the sound, then check how it sounds normalized.
- Compare with reference tracks at equal loudness.
Example
Two masters of the same beat in A minor: A at −7 LUFS, B at −10 LUFS. Normalized to −14, B keeps more punch on the kick and 808; A seems more compact but less dynamic. The choice depends on the genre.
Real-world example
Metallica's “Death Magnetic” (2008) became the symbol of the “loudness war”: the master was publicly criticized for clipping and distortion due to excessive volume.