Fatigue crack propagation can significantly reduce component life and potentially lead to failure. This study aims to evaluate the fatigue life of the 2024-T3 aluminum alloy under variable loading by transforming it into an equivalent constant-load problem, thereby avoiding cycle-by-cycle calculations. The framework relies on a two-parameter fatigue model that accounts for both the maximum total stress intensity factor Kmax _ tot and the magnitude of the total stress intensity factor ∆Ktot. Initially, plastic-zone interaction effects are neglected to establish an equivalence between variable and constant loading via the driving-force model. The Willenborg model is then employed, generalized by Meggiolaro and Castro and subsequently Gallagher, to determine the equivalent stress Δσeq that yields a comparable crack-growth rate under constant loading. The study outlines the transition from variable to equivalent constant loading, with the potential inclusion of crack-closure effects as needed. The calibrated parameters (CT,p,q) are obtained from experimental da/dN versus ΔK data for 2024-T3. Preliminary validation shows encouraging agreement with experimental results for two loading sequences. In conclusion, the proposed methodology provides a robust estimate of fatigue life under variable loading, preserving the main propagation mechanisms while simplifying industrial-scale calculations.