Automatic calibration of an eye tracking system involves capturing a plurality of eye measurements, wherein each eye measurement relates to a corresponding eye gaze position of a human eye; determining a set of statistics data from the plurality of eye gaze measurements; comparing the set of statistics of eye gaze measurements with a set of statistics relating to a plurality of pre-measured eye gaze positions of at least one person; and as a result of the comparison, determining a calibration correction factor which, when applied to the statistics of eye gaze measurements, gives an optimum match between the statistics of eye gaze measurements and the statistics of predetermined eye gaze positions.