An analysis of the influence of undercutting on the stress concentration factor for undercut gears using the finite element method is presented. The models used are in the shape of a whole gear with three teeth. The middle tooth is loaded assuming single-tooth contact. Thirty seven finite element models were used to compute stress concentrations in gear teeth. The results for non-undercut gears were compared with the Dolan and Broghamer results, and were not more than 9.5 percent different. The results are expressed in the form of a linear relationship giving the stress concentration factor at the root fillet as a function of the geometry of the tooth. It has been verified that this equation is an accurate formula for both undercut and non-undercut gears with nominal proportions. / Master of Science