We present a method to determine accurate and absolute Molecular weight distributions (MWDs) as well as absolute concentrations of the individual macromolecular components in mixtures of polymers of the same monomer class yet differing in their end groups. Data gained from size exclusion chromatography coupled online to refractive index (RI) detection and electrospray ionization mass spectrometry (ESI-MS) are processed by a sophisticated computer algorithm based on the maximum entropy principle. The procedure yields, for the First time, absolute molecular weight distributions of each component corrected for chromatographic band broadening. Molecular weights of tip to 10 kDa are accessible with a conventional quadrupole ion-trap mass analyzer. The method is applicable to variable polymer systems regardless of the monomer class and without the need for an external calibration or additional model assumptions. 11 was validated using binary and ternary mixtures of poly(methyl methacrylate) carrying labile functional groups. For the ternary mixture, maximum deviations of the reconstructed molecular weight averages and mass concentrations from the original values were 8% and 5%, respectively.