Dosimeters supplied in large batches generally have intrinsic non-uniform response characteristics that can be improved by a technique of individual dosimeter characterization. Pre-use irradiation of radiochromic dye film dosimeters provides a simple method for reducing the standard deviation and error in making absorbed dose assessments. Through a simple pre-use uniform irradiation of a selection of dosimeters to a dose of 1.0 kGy, variability in the dosimeters' optical densities at a given wavelength and film-to-film variation in thickness are automatically excluded in an interpretation of subsequent unknown doses in the range 1–20 kGy. This technique reduces by about a factor of four the nominal error associated with routine radiochromic dye film measurements.