A simple method is proposed for using a size-exclusion chromatograph equipped with both concentration and light-scattering detectors to calibrate other chromatographs having only concentration detectors. The method is developed and demonstrated for poly(ethylene terephthalate) in methylene chloride/dichloroacetic acid. It is shown that, in addition to circumventing the need for a light-scattering instrument on other chromatographs to be used for the analysis of PET, precision and accuracy of results are improved over those obtainable with light-scattering detection. The method uses averaging of the light-scattering detector data to establish a correlation between the molecular weight of the polymer of interest and the molecular weight of polystyrene at each retention volume. This correlation can then be used for other instruments employing the same mobile phase and only a concentration detector. Although the method assumes the validity of the universal calibration curve, the actual curve is not required, nor are Mark-Houwink constants or intrinsic viscosities.