Water analyses typically result in numerous characteristic values. The bunch of parameters hamper temporal or spatial comparisons of different samples. In order to facilitate the evaluation and interpretation of hydrochemical data, hydrogeologists use various special diagrams. One of them is the Schoeller diagram, in which concentrations of different species are plotted on logarithmic scales. Entries of an analysis are connected and form a characteristic signature. In the Schoeller diagram, parallel or subparallel signatures indicate relatedness of waters. Here we present the idea of standardized Schoeller diagrams: different logarithmic axes are shifted with respect to each other, in order for the signature of a selectable sample to form a straight line. This standardization greatly facilitates the comparison of water samples to the chosen standard and increases the informative value of a Schoeller diagram. As to our knowledge, there is no software that could generate standardized Schoeller diagrams, we have developed a Matlab tool for this purpose. The tool is available for free and allows fast generation of standardized Schoeller diagrams with many possibilities to implement user-specific wishes. We hope that this tool will contribute to a wider use of Schoeller diagrams.