The paper provides first systematic analysis of properties of all mechanically compatible and electrically neutral domain walls in tetragonal, orthorhombic, and rhombohedral ferroelectric phases of BaTiO3. Polarization and strain profiles within domain walls are calculated. Domain-wall thicknesses and energy densities are estimated for all mechanically compatible and electrically neutral domain-wall species in the entire temperature range of ferroelectric phases. The model suggests that the lowest-energy walls in the orthorhombic phase of BaTiO3 are the 90° and 60° walls. The calculation indicates that the lowest-energy structure of the 109° wall and few other domain walls in the orthorhombic and rhombohedral phases resemble Bloch walls known from magnetism.