One key aspect of efficient transport is load factor: the load carried compared to the maximum load that could be carried in a load unit (e.g. a vehicle). The purpose of this study is to develop an approach that will clarify and describe ways in which shippers can measure load factor. Drawing on existing literature and understanding gained from empirical data the proposed approach uses the load factor model, which structures measurement of load factor overall and at several levels (packaging, shipping, vehicle, fleet) as the ratio of required to available capacity. Shipping level includes utilization of purchased capacity, which is of special interest to shippers. For applying the model in practice, calculation methods linked to availability of data are presented. Calculations of volumetric load factor from two cases illustrate the methods. This paper’s detailed descriptions of how shippers can measure load factor provide calculation structure as well as transparency. Measuring load factor is of interest to evaluate efficiency, particularly since load factor is related to transport costs and environmental performance.