The development and optimization of filet atomization in the port-injection and direct-injection systems of automobile engines are important in terms of improving the fuel combustion performance and thermal efficiency of engines. An effective method of achieving this goal is computational prediction. However, a practical method of simulating the continuous primary and secondary spray breakups and the spraying behavior has not yet been developed. In this study, we develop an integrated computational method for the total fuel atomization process of the injector nozzle. This new computational approach takes into account the nozzle internal flow using the volume of fluid (VOF) method and the spray flow to the engine cylinder using the discrete droplet model (DDM). We recently developed a coupling code called the VOF-DDM bridge tool to transfer the flow-field data obtained using the VOF method to the initial numerical conditions of the DDM. In the VOF-DDM bridge tool, the initial diameters for liquid breakups from a liquid column and a liquid sheet are evaluated using different methods. The proposed method is applied to spray flows from hole injector and swirl injector systems. The experiments of the spray flow from hole and swirl injectors are performed to assess the validity of the proposed numerical simulation. The present numerical method predicts the spray behavior for relatively low fuel pressure and the qualitative behavior for hole injector systems, such as the increase in spray tip penetration with increasing fuel pressure. However, the method encounters problems at high filet pressure. In the simulation of a swirl injector, the predicted spray tip penetration and spray angle agree reasonably with corresponding experimental results.