Surface tensions (gamma) and bulk pressure-volume-temperature (PVT) properties were measured for linear perfluorinated alkanes. The Cahn-Hilliard density gradient theory combined with an equation of state modeling of bulk properties was used to describe the temperature and MW dependence of gamma for the perfluorinated alkanes. It is implicitly assumed in the theory that the surface has the same composition as the bulk, so it is known that the theory should fail in cases where significant orientation occurs at the free surface. Surface excesses of CF3 chain ends were found to contribute negligibly to the measured surface tensions for perfluorinated oligomeric CF3(CF2)(n)CF3 to high molecular weight (MW) poly(tetrafluoroethylene) (PTFE). The surface tension of a high MW PTFE (MW ca. 70 000 g/mol) sample was measured for the first time using the modified Wilhelmy method. Theory could adequately reproduce the experimental gamma and furthermore show that essentially the same results are predicted for an ultrahigh MW PTFE sample for which experimental values of gamma could not be obtained because of the high melt viscosity. All of the perfluorinated alkane data were combined on a universal plot scaled by the PVT fitting parameters. The utility of the universal curve is that, for homopolymers for which PVT data are available, gamma can be predicted at any temperature and MW to within 2%, with minimal computation.