Today, the economic crisis is putting enormous pressure on most organizations. It evolves in a crucial competitive environment with a multiplication of production cycles and implementation on the market. Due to this dynamism, organizations must be scalable and agile by adopting an approach that aims to make the process model of a given organization reusable. Indeed, according to the new paradigm which is called “Design by reuse” the models of configurable processes, gain recently in importance since these models have the capacity to represent explicitly the common parts and variables of identical processes in a customizable model. These configurable process which group several execution choices through a variation point called configurable connector will present an uncertainty related to the execution (or not) of the conditional tasks in a process model. In this paper, we propose a measure based on Shannon's entropy in order to model the uncertainty of the process at design time to guide configurable business process designers and analysts in developing and improving processes to be more predictable, less complex, and more understandable.