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.
