The SMx (x= 12, 8, or D) universal solvent models are implicit solvent models that can be used to compute the solvation free energy at 298.15 K using electronic structure calculations. Fundamentally, the solvation free energy is an important thermophysical property, and corresponds to the transfer free energy of taking a single solute from a non-interacting ideal gas state to solution (at infinite dilution) at the same molar density. In going from a non-interacting state to a state with a single solute molecule in solution, the solvation free energy is representative of the solute-solvent interactions in solution. If the solvation free energy of a solute is computed in two different solvents, they can readily be used (via a thermodynamic cycle) to compute the transfer free energy between the two solvents. This transfer free energy is directly related to the partition coefficient, which can be used to relate to the relative composition of the solute in the two (immiscible) solvents at equilibrium, or more generally can be used to compare the relative affinity of the solute for the two solvents.