The correct calculi of surface tension and solubility parameters are of paramount importance for many fields of chemical engineering and materials design, such as encapsulation methods (which use the mean field theory), dispersion of nanopowders, phase compatibility in chemical blends and nanocomposites, among others. The solubility parameters play a key role in these applications along with the surface tension. Until now, the relationship between solubility parameters and surface tension was only indirect, through the Skaarup-Beerbower formula, although well-known physicochemical rules, such as Stefan's rule, could be applied to them directly, as shown in this study. The prediction of both the solubility parameters and surface tension within chemical groups can be obtained with high accuracy using critical temperature and molar volume, parameters easily found in the literature. The proposed rules are original, simple and have direct practical applications for the development of new materials. POLYM. ENG. SCI., 59:E312-E321, 2019. (c) 2018 Society of Plastics Engineers