We present a new set of interatomic potentials for modelling the BaTiO₃ perovskite system. The potential model is fitted using multiple parameters to a range of experimental and ab initio data including the cohesive energy and lattice parameters of BaTiO₃, BaO and rutile TiO₂. This procedure provides internal consistency to the potential model for studying the energetics of the defect chemistry of BaTiO₃. This is tested by examining rare-earth cation doping in BaTiO₃ and considering all five possible compensation schemes. Our simulations are in agreement with experiment and predict small rare-earth cations to dope exclusively on the Ti site; medium sized rare-earth cations to dope on both the Ti and Ba sites and large rare-earth cation doping exclusively on the Ba-site. For Ba-site substitution the simulations predict electron compensation to be energetically unfavourable compared to the formation of Ti vacancies.