The most critical point of gear design is bending stress which occurs on trochoid region of the gear. The high bending stress on trochoid region of the gear causes the tooth failure and the fatigue life of gear reduces. For this reason, bending stress must have lower magnitude as much as possible. In this study, to calculate bending stress, graphical method is proposed. It is based on DIN3990 and searches critical point in every point of trochoid region. First of all, for standard gear, stress is calculated with using the DIN 3990 standard and graphical method. Besides finite element analysis is used for validation of method. After validation, bending stresses are investigated for different gear parameters with finite element analysis and graphical method. It is evaluated that rack cutter tip radius is the most effective parameter on root stress. When increasing tip radius of rack cutter, the value of bending stress decreases 30%. It is seen that graphic method could be used with high reliability in gear stress analysis especially for gears with especially non-standard parameters.