What Is LUFS? Understanding the International Loudness Standard

LUFS: A Loudness Unit Based on Human Hearing

LUFS (Loudness Units relative to Full Scale) is the loudness unit defined by the International Telecommunication Union in Recommendation ITU-R BS.1770. The key difference from traditional dB peak metering: peak level only captures the waveform’s instantaneous maximum, while LUFS applies a hearing-model frequency weighting (K-weighting) and averages loudness over the whole program — much closer to “how loud it actually sounds.”

BS.1770 also defines true peak (dBTP) measurement: oversampling reveals the real waveform peaks that occur between digital samples, preventing clipping that would otherwise appear only after format conversion.

Why Quiet Passages Don’t Drag the Number Down

BS.1770 measurement includes a gating mechanism: passages below a threshold (such as pauses in an interview) are excluded from the average. That is why an episode with plenty of silence still reports a loudness figure that correctly reflects the spoken parts.

Target Values by Field

What It Means for Editing

Before you merge material from different sources — interview recordings, theme music, ads — align each segment to the same loudness target first, so the result doesn’t lurch between loud and quiet. On export, land the average loudness near your platform’s spec and leave -1 dBTP of true-peak headroom, and the platform won’t have to re-process your audio.

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References

  1. ITU-R BS.1770-5, “Algorithms to measure audio programme loudness and true-peak audio level,” International Telecommunication Union.
    https://www.itu.int/rec/R-REC-BS.1770
  2. EBU R 128, “Loudness normalisation and permitted maximum level of audio signals,” EBU technical document.
    https://tech.ebu.ch/docs/r/r128.pdf
  3. Spotify for Artists, “Loudness normalization.”
    https://artists.spotify.com/help/article/loudness-normalization