The agent - based modeling of freight transport that captures both the variety of actors and their complex decisions has not made as much progress as in passenger transport. Efforts towards agent-based models must include firms. However, the synthesis of a firm population in the context of urban freight transport has gotten little attention in literature. This research focuses on synthesis of a firm population for urban freight transport demand model. It uses literature review to define the firm agents and specifies a general population synthesis model based on iterative proportional updating (IPU). The model is then implemented on a case study on the province of South Holland. The utilized data is open, free-of-charge data offered by the Central Bureau for Statistics (CBS) of The Netherlands. The synthesis uses a sample-free, indicator-based approach to initialize the IPU-based model. The results show correlation between firms’ distribution and urban density of neighborhoods for most of the population. However, the suitability of a neighborhood to host a firm type has a more nuanced definition that cannot be encapsulated in a single indicator. More robust, economic-sector specific indicators are needed to disaggregate firm agents to neighborhoods and finer levels. Further research into IPU-based, sample-free firm synthesis models is recommended.