Three-dimensional (3-D) simulations on entire slot coating systems including regions inside the slot die and in coating bead are performed for correlating die internal and external flow fields. A CFD solver based on the finite volume method with a volume of fluid scheme is employed to investigate coating flow dynamics with free surfaces and menisci in the coating bead region. Operability windows for a Newtonian coating liquid in this process are determined using the simplified viscocapillary model and experiments, and then some flows states are quantitatively verified with 3-D model. The results from the 3-D model show that the final coating thickness with edge beads is satisfactorily predicted, and agree with experimental observation and the relationship between die internal and external flow features is closely linked.