Using the extension of the concept of universal calibration parameter, yielding a relation between the hydrodynamic volume of molecules and the elution volume in size exclusion chromatography (SEC), to retention coefficients in ultrafiltration (UF), we propose a direct calibration of UF membranes against chromatography columns. Plotting the retention coefficient by one given UF membrane of a series of probe molecules versus their elution volume in SEC chromatography provides a calibration curve for this membrane. For a wide range of retentions, such calibration can be directly used to predict the retention of any molecule: one only needs to measure its exclusion volume by the SEC column, and read the retention by the calibrated membrane on the calibration curves. The method has been tested with dextran and PEG for the calibration, and milk proteins as test molecules, for three different membranes. The predicted values of the retention are in rather good agreement with those experimentally measured in a UF cell. (C) 2009 Elsevier B.V. All rights reserved.