Wayfinding is a basic activity that people do throughout their lives as they navigate from one place to another. Many theories of spatial cognition have been developed to account for this behavior. However, most of the computational models focus on knowledge representation (for example, cognitive maps) and do not consider the process of how people structure wayfinding tasks and space. In this paper we present a computational method to compare the complexity of wayfinding tasks in built environments. As a measure for such complexity, we use a simple wayfinding model that consists of two critical elements: choices and clues. We show that elements of people's perception and cognition can be used to determine the elements of the wayfinding model and, therefore, to compare the complexity of wayfinding tasks in built environments. A case study of wayfinding in airports demonstrates the applicability of the method. The integration of this method into the computational design process of built environments will help to identify architectural problems with regard to wayfinding prior to construction.