An electrochemical biosensor analysis system is provided for analyzing a sample liquid, comprising a biosensor having an electrode structure made of at least two electrodes, a test field, covering the electrode structure and capable of absorbing the sample liquid, and a defined sample application surface on the top side of the test field. The system also includes an analysis instrument comprising an evaluation unit for determining the desired analysis data. The analysis instrument comprises an AC resistance measuring device for measuring an AC resistance value between two electrodes of the electrode structure by means of an area compensation measurement. The measured AC resistance value is used, in the determination of the analysis data, as a measure of the partial area of the effective electrode structure area wetted by the sample liquid.