Abstract: An arrangement as well as a method for calibrating a spectrometer for measuring spectral fractions of a substance in the context of chemometrics or chemometric processes with a spectrometric apparatus for measuring spectral fractions of the substance to be examined as well as with a calibration unit, by means of which a calibrating of the spectrometric apparatus and/or measurement data based on measured spectrometric data is performed, characterized by the following steps: a) measuring a totality of spectral fractions X and/or corresponding substance concentrations of the substance to be examined; b) storing the totality of the measured spectral fractions X in a memory module as spectrometric measurement data in the form of a multidimensional coefficient vector; c) automatic extracting, from the totality of the measured spectral fractions X, of spectral fractions Xrel physically relevant for the particular measuring procedure via an automatically running, iterative, estimation method furnished in the calibrat