Analytic expressions for the fractions of nonbonded association sites have been derived for different cross-association models in the framework of the statistical association fluid theory (SAFT). The comparison with solutions of a chemical theory for association shows that the solutions of both theories are equivalent. Therefore, simple approximations obtained from the chemical theory can be applied to cross-association models of SAFT. Analytic solutions simplify the application of SAFT in chemical engineering modeling. For other cross-association models, for which the fraction of nonbonded sites cannot be obtained analytically, an efficient alternative numerical solving procedure is described.