We investigated the effect of porosity and crack size distributions on the fracture behavior of porous glass through a combined finite element and fracture mechanics method. Simulations showed that the effect of crack size distributions on the change in fracture strength with porosity decreases as the pore size to crack size ratio increases. For a pore size to crack size ratio of  >∼4, the average failure initiating crack size decreases with increasing porosity. Two regions were defined to describe the relationship between porosity and fracture strength: Region I for porosity less than 20 vol.% and Region II for porosity greater than 20 vol.%. Simulation results were directly compared to the porous glass experiments from the literature.