The vapor pressure of a series of perfluoropolyethers (PFPEs) was estimated from the weight loss measured in a standard thermogravimetric analyzer (TGA). A relation linking the coefficients describing the vapor pressure dependence on temperature to the molecular weight was obtained from the data measured on fractions with a narrow molecular weight distribution. Based on this relation, a simple method predicting the vapor pressure of a mixture of PFPEs from the molecular weight distribution can be applied to the whole range of grades. (C) 2011 Elsevier B.V. All rights reserved.