When conducting lift traffic analysis, one of the key modelling choices is the passenger capacity: the limit on the number of passengers in a lift car. A widely used convention in the elevator industry is the 80% rule, according to which lifts are assumed to be loaded to no more than 80% of their rated capacity. However, the interpretation of this rule varies across practitioners and methods. Lift car loading is likely influenced by multiple factors, such as cultural norms, traffic conditions, rated capacity, and the building segment. Although the 80% rule is a recurring topic in professional discussions, published measurement data remains scarce. For this study, automatic passenger count data from 34 office buildings was analyzed. Some offices included multiple lift groups, resulting in a total of 52 lift groups. The measurements were conducted in Europe, Asia, the Middle East, Australia, and North America.