A joint research team at Argonne National Laboratory used laser powder bed fusion to fabricate Ti-6Al-4V specimens containing internal pores, which were mechanically tested to fracture under in situ synchrotron radiation tomography. Results show that cracks initiating from sharp features of pores accelerate with deformation, dominating the fracture behavior. Parameters including crack growth rate, tortuosity, propagation direction, and multiplicity were used to calibrate the Rice-Drugan-Sham crack growth model, with propagation angle having the most significant impact on fracture strain. By isolating contributions in the crack growth model, differences in crack propagation behavior under three heat treatment conditions were quantified. Finite element analysis verified that accurate calculation of tensile strength as a function of strain and fracture strain requires considering crack propagation effects, providing a more precise quantitative method for predicting mechanical performance of components containing pores.