With advances in design and manufacturing, the cooling performance of daytime radiative cooling materials has progressively improved. However, there has not been an effective method for comparing the cooling performance of the materials tested in different geographical locations and laboratories. Here, we present a simulation-based method, consisting of the basic radiation theory, the standard solar spectrum, and six standard model atmospheres, for comparing the cooling performance of different daytime radiative cooling materials. The proposed simulation-based comparison method was then used to compare four representative daytime radiative cooling materials selected from the literature. The results demonstrated the effectiveness of the proposed method in comparing the cooling performance of different radiative cooling materials tested under different environmental conditions. With the proposed comparison method, the engineers can choose the most suitable daytime radiative cooling material for a specific environment. •A method for comparing performance of different radiative cooling materials was proposed.•The method consisted radiation theory and standard solar spectrum and model atmospheres.•Representative radiative cooling materials from literature were compared using the method.