An optimal performance film cooling implies a high cooling effectiveness along with a wide surface cooling coverage. During the past decades, film cooling effectiveness has been well defined with a specific formula to evaluate the quality of a cooling system. However, despite numerous research on film cooling, there is still no explicit parameter to quantify how well a coolant film is spread over a hot surface. This work introduces a new coefficient namely cooling uniformity coefficient (CUC) to evaluate how well a coolant film is spread over a surface that is being cooled. Four different cases at two blowing ratios of 0.5 and 1.5 are studied. Three cases are ordinary single jets with different cross sections whereas the fourth one is a novel combined-triple-jet, sometimes called anti-vortex-holes, introduced in a previous work. The cross sections of all four cases were kept the same to have equal coolant mass flow rate. This article suggests that CUC is a necessary parameter in order to have a well performance film cooling system, in addition to the film cooling effectiveness. Indeed, CUC evaluates how well coolant films are spread over hot surfaces which is very important from thermal loads and thermal stress points of view.