A method and system for evaluating structural defects in metals is provided. In one embodiment, the method recognizes that the acceptability of a given defect is principally determined by the four basic parameters of operating temperature, operating stress, defect area, and defect shape. Ranges are established for each of these four basic parameters, and intermediate values within these ranges are selected to create a series of index value data sets. The method evaluates these index value data sets by calculating a life cycles estimate for each. Using statistical methods, the life cycles results are analyzed to determine the effect each of the four basic parameters has on the life of a component with a defect. Understanding the relationship between these four basic parameters and life cycles enables the method to provide an interpolation algorithm for finding the life cycles for any component having a defect.