This study calculated an approximate metastable defect concentration necessary to induce precipitation of TiO2 in SrTiO3. Atomic force microscopy was used to characterize the average relative energies of interfaces in the TiO2/SrTiO3 system. These values were taken as the basis for describing the relevant interfacial thermodynamic terms associated with the activation energy for precipitation. The corresponding average Sr-O vacancy pair defect concentration necessary to induce precipitation in the grain boundary was calculated.