Methods for calibrating an irradiation device for an apparatus for additively manufacturing three-dimensional objects include generating at least two first and two second calibration patterns, in at least two different first positions and at least two different second positions; determining position information relating to the positions of the calibration patterns; generating a calibration quality value relating to a calibration status of the irradiation device; simulating at least two first calibration patterns and at least two second calibration patterns based on at least one changed irradiation parameter; determining a calibration quality value for the simulated calibration patterns; and repeating the simulation and determination of the calibration quality value until a maximum or minimum calibration quality value is reached.