A method for calibrating apparatuses for determining the moisture content of products based on capacitive measurements comprises the following operating steps: Inserting a device (1) for simulating the dielectric properties of products in a measuring area of an apparatus (2) to be calibrated; taking a capacitive measurement with the apparatus (2) while the device (1) is inserted in the measuring area; modifying the device (1) settings at least once and taking the capacitive measurement again, for each different setting value; comparing each capacitive measurement taken this way with a corresponding known reference capacitive measurement; calibrating the apparatus (2) based on this comparison. In turn, the device used in the method comprises at least a first receiving antenna (3), at least an electric terminal (4), in practice electrically connectable to the apparatus (2), and at least one adjustable impedance (5) for modifying the settings of the device (1), and which is electrically connected between the first antenna (3) and the electric terminal (4).