SDCM (MacAdam Ellipse) (SDCM)

SDCM (Standard Deviation of Colour Matching) expresses chromaticity tolerance in MacAdam ellipse steps — how tightly the actual white point of LEDs clusters around the nominal target. Within 3 SDCM, color differences between adjacent fixtures are essentially invisible; at 5 SDCM, side-by-side tint variation may be noticeable on white surfaces; beyond that, rows of fixtures can look patchy. Quality manufacturers control this through LED binning at purchase and state a fixture-level tolerance such as ”≤ 5 SDCM”. The metric matters most where many fixtures are viewed together against uniform backgrounds — supermarket ceilings, facades, sports halls — and least in visually busy industrial environments.