This book mainly comprises of the transmission error analysis of spur gears with an involute profile using nonlinear Finite Element analysis. For obtaining a gear tooth geometry, a program for the profile of involute spur gear has been developed in Microsoft Excel using the Macros module in Visual Basic language for any number of teeth, module, and Pressure angles. For establishing the procedure of nonlinear contact problem using ANSYS workbench and later validated on test rig experiment. The results obtained has been validated with the theoretical and experimental rig, the procedure of selecting parameter and approaches are briefly explained making ease to users for continuing research and advancements in a similar area.