<p>Most fatigue failures initiate at the surface or subsurface layer of components in aerostructures. Surface modifications have emerged as a critical pathway for enhancing component-level fatigue resistance. Optimizing surface processing techniques and parameters requires a systematic characterization method for surface quality assessment. This study establishes a quantitative framework for predicting the fatigue limit by integrating mechanistic analysis with multi-parameter mathematical modeling. The predictive capability of the proposed model is evaluated by comparing experimental results from different configurations, including Nickel superalloy samples processed by shot peening (SP) and surface severe plastic deformation (S²PD), M50NiL samples processed by case hardening, and pure Fe samples with a gradient nanostructure layer (GNsL-Fe), with the results from the model. The predicted results agree well with the experimental results, confirming the appropriateness of this model. The model can be used to estimate the fatigue limits of metal components and support the improvement for surface processing techniques.</p> Graphical Abstract <p></p>