Abstract: A colorimeter operating on color matching logic concerned with a process of quantitatively analyzing a known substance by finding the color signature of the colored solution of that substance and matching it or interpolating it with the color values provided in the look-up table for that substance for determining the concentration of the substance in question. A memory means coupled with a microprocessor or a computer stores the calibration commands, computational routines and comparison logic and stores a plurality of color data corresponding to each biochemical, clinical pathological or chemical test for the substances that can possibly be quantitatively determined by the said colorimeter and the said data is stored in the form of look-up tables.