LUFS is a measurement that smart people came up with to express level in a way that’s similar to human hearing. -10LUFS and lower is loud. -20LUFS and higher is quiet and -14LUFS is just right…well, so they say. Many streaming services set their normalization levels to about -14. Meaning, if ‘loudness normalization’ is on it will set the relative level of the music you are listening to -14LUFS regardless of what level the music was provided by the artist or record label. Most services will keep tracks at a relative LUFS level when listening to an album but for playlist or random shuffle, it will adjust all songs to a LUFS level set by the service.

The first thing to note with this is that there is no standard. All streaming music services set their own level standard so you can’t deliver a master that will conform to all services. Beyond that, most streaming services allow you to turn off (or on in Apple Music’s case) loudness normalization so if your master is set to a lower level and other songs in the same genre are not, your masters will sound significantly quieter. As of the end of 2021 almost 100% of the top 100 streaming songs in Rock, Pop, HipHop, Alternative and RnB are mastered much louder than -14LUFS so your songs will sound much quieter in a playlist with those songs when loudness normalization is turned off. Why is that an issue? Well, simply put, if all of the preceding songs are loud and your song comes on and it’s significantly quieter than the others, rather than raising the volume the listener might just skip the song. This was learned years ago from radio and it’s what led to the eras of ‘loudness wars’.

This might change in the future. If streaming services don’t allow you to turn off loudness normalization (like YouTube and Soundcloud) or somehow a loudness standard is adopted but for now it’s still, for the most part, loud masters.