In this work we have applied a fully ab initio approach to model the electrical-and thermal-transport properties and thermoelectric figure of merit of orthorhombic CaTiO 3 , tetragonal SrTiO 3 , and rhombohedral BaTiO 3 . The differences in the electrical properties are dominated by the electrical conductivity, and the piezoelectric scattering facilitated by the non-centrosymmetric R3m spacegroup of BTO results in a significant suppression of the transport. We also predict that doping levels on the order of 10 21 cm -3 are required to obtain reasonable power factors, while larger n have a detrimental impact on the Seebeck coefficients. The lattice thermal conductivity plays an important role in determining the ZT , with a steep temperature dependence resulting in the benchmark ZT > 1 only being attained at high temperatures. Analysis of the κ latt demonstrates that differences in structure and chemical bonding, rather than the mass of the A-site cation, is the key descriptor, and that the relatively high thermal conductivity of STO is due to large phonon group velocities.