LKFS (Loudness, K-weighted, relative to Full Scale) is the loudness unit used in the ATSC and ITU world, and it is numerically identical to the EBU's LUFS — one LKFS equals one LUFS, only the name differs by standards lineage. It measures perceived loudness via the K-weighting filter and gating defined in ITU-R BS.1770, on a scale referenced to digital full scale, so values are negative. US broadcast targets -24 LKFS under ATSC A/85 and the CALM Act. If you see LKFS in an American spec sheet and LUFS in a European one, they are the same measurement; the dual naming is a frequent source of needless confusion.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
LKFS and LUFS are the same unit under two names, and mixing up specs that use them causes needless loudness rework. Volume 4 explains LKFS within its loudness chapter: BS.1770 measurement, ATSC A/85 and EBU R128 targets, true-peak limits and the delivery numbers each platform expects. Written by Nikolay Sapunov, CEO at Fora Soft.
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