Several types of implants, plates, and screws have been developed for corresponding bone fractures at different sites. To understand the mechanical behavior of a bone plate and to provide surgeons with suggestions for selecting screw positions, this study aimed to create an APP to provide presurgical planning using a computed tomography (CT)-based finite element model. This model was validated using a compression test of synthetic sawbones. Furthermore, the specific APP was established using the COMSOL application builder to calculate the stress and strain of the implant under different screw positions. This APP reveals how the number and location of screws affect the stress distribution of the implant. It can provide clinicians with preliminary reference information before surgery.