The definition of preliminary project cost estimates is one of the key aspects of investments in the real estate field. This kind of estimates plays a fundamental role in the decision-making process defining whether to proceed with the project. However, the definition of accurate estimates in preliminary phases is still an open issue and several researches have been developed to improve the performance of the process. Most of the researches are focused on the introduction of digital methods that are able to improve performance both in terms of precision and effort reduction. This paper is focused on the comparison between two traditional estimating methods used in the preliminary project phase and a digital method based on Building Information Modeling processes and instruments, to understand the impact of digital practices on the traditional estimating processes.