A method for determining a remaining useful life of a bearing having a surface defect includes determining a defect size of the surface defect based on oscillations of the bearing. The method also includes determining, based on the defect size, at least one of the principal stresses or a contact force of the bearing caused by the surface defect. The method also includes determining the remaining useful life of the bearing based on at least one of the principal stresses and/or the contact force.