Gravitational studies have been a key instrument in analyzing spatial flows. In this research, we will be highlighting the relevance of the data related to population and distances between urban centres in assessing the urban balance of human settlements using a gravitational law. Our hypothesis stipulates that an urban centre's real urban population is different from the one included in its theoretical geographic boundaries. The assessment process is based on the functional weight of various urban centres. We will implicate the urban infrastructure then each centre's functional "Areas of Influence" in the entire region. We aim to test the validity of the mathematical Reilly law on our study corpus, which is Makkah Province, using the mentioned parameters. In addition, there was an attempt to model the real urban attraction of cities. Finally, the calculation results of the urban centres attractions are pulled down to be projected on the Geographic map of our Case Study. The study findings reveal a discordance between the real weights and sizes of the urban centres and the theoretical ones, which discloses a clear unbalance of the urban system that needs to be addressed.