The research presents a novel strategy to locate and quantify damage, as well as estimate their geometry damage sizes. The strategy is implemented to estimate the size of geometry damage (width and depth) based on the damage library and frequency changes between healthy and damaged Euler-Bernoulli cantilever beams. Firstly, a geometry damage library is built by a concept of correlation of 2D and 3D finite element (FE) models using a frequency shift coefficient (FSC). Secondly, FSC-based algorithm is implemented to localize and quantify damage along the beam structure. FSC algorithm is employed as a particle swarm optimization (PSO) solver to determine the best-fit minimized values that represent damage position and severity. Finally, the severity of damage is used to estimate the size of the damage from a damage library. The strategy is demonstrated by testing the experimental beam and estimating damage parameters from a real geometry damaged case.