LUFS (Loudness Units relative to Full Scale)
The unit platforms use to measure how loud something actually sounds, so YouTube and Spotify can level everyone to the same volume.
See it
What it is
LUFS measures how loud something sounds to a person over time, not how tall the waveform gets. The measurement is K-weighted, meaning it leans on the midrange your ears care about and shrugs at deep sub bass. The number you usually quote is integrated LUFS: one figure for the whole program, averaged over everything after the quiet bits are gated out.
You reach for it at the very end, on export. There is no single streaming number, so treat each destination separately. Spotify has long published a playback normalization level around -14 LUFS and YouTube sits in roughly the same neighborhood, while Apple Music normalizes with Sound Check rather than handing you an authoring target. Spoken-word podcasts usually land around -16 LUFS, and broadcast is written down properly: -23 LUFS under EBU R 128, -24 LKFS under ATSC A/85. Platform figures drift, so check the current published spec for the thing you are actually delivering rather than trusting a number you memorized (these were the commonly cited values as of 2026). Any DAW loudness meter, or a free tool like Youlean Loudness Meter, will read your file back to you.
Gotcha: loud no longer wins. Platforms normalize playback, so a squashed master gets turned down to the same level as everyone else and just sounds flat and airless next to them. And LUFS says nothing about peaks: you can hit -14 LUFS and still clip, which is why you also cap true peak at about -1 dBTP.
Ask AI for it
Master this audio for [platform/deliverable]. Use that destination's current published loudness and true-peak requirements; if it publishes no authoring target, state the target you chose and why. Measure integrated loudness first, then apply gain and transparent limiting to reach it. Preserve the dynamics (do not squash the mix just to hit a number), and report final integrated LUFS, loudness range (LRA), and the true peak of the encoded delivery file, not just the project.