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AudioGLOSSARY

LUFS — Loudness Units

Definition

LUFS (Loudness Units relative to Full Scale) is the unit of programme loudness measured with the algorithm of ITU-R BS.1770, which applies a frequency weighting (K-weighting) modelled on hearing and integrates the level over time. One LU equals one dB. Broadcast targets are −23 LUFS in Europe (EBU R128, with a tolerance of ±0.5 LU, or ±1 LU for live programmes) and −24 LKFS in the United States (ATSC A/85, made mandatory by the CALM Act). Streaming services normalise playback to their own targets, commonly reported as −14 LUFS for Spotify, YouTube, TIDAL and Amazon Music and −16 LUFS for Apple Music. A peak meter shows only the maximum level, while a loudness meter reflects how loud the content is perceived.

In the field

EBU Tech 3341 defines three measurement windows: momentary (400 ms), short-term (3 s) and integrated over the whole programme. Delivery specifications refer to the integrated value, while the momentary reading fluctuates constantly and serves as a guide during mixing. A programme at −23 LUFS integrated usually leaves enough margin below the −1 dBTP true-peak limit of EBU R128 to keep its transients without heavy limiting.

Sources

  • ITU-R BS.1770-5 (2023) : algorithme de mesure de la sonie et de la crête vraie · itu.int
  • EBU R 128 : cible −23 LUFS, tolérance ±0,5 LU (±1 LU en direct), crête vraie maximale −1 dBTP · tech.ebu.ch
  • EBU Tech 3341, « Loudness Metering: EBU Mode » : fenêtres momentanée 400 ms, court terme 3 s, intégrée · tech.ebu.ch
  • Auphonic, « Loudness measurement and normalization with EBU R128 (Calm Act, ATSC A/85) » : ATSC A/85 à −24 LKFS, CALM Act · auphonic.com
  • Spotify for Artists, Loudness normalization : normalisation de la lecture à −14 LUFS · support.spotify.com
  • Fora Soft, LUFS targets per platform : −14 LUFS (Spotify, YouTube), −16 LUFS (Apple Music) · forasoft.com
  • Production Advice, « TIDAL loudness » : normalisation de TIDAL vers −14 LUFS · productionadvice.co.uk
  • Production Advice, « Amazon Music loudness normalization » : normalisation d'Amazon Music vers −14 LUFS · productionadvice.co.uk