The present disclosure relates to a method and a system for estimating a radar calibration matrix. According to the method, an initial calibration matrix is received, and via a radar sensor, radar detections are acquired from the external environment of the radar sensor. A plurality of beam vectors is determined which are derived from the radar detections, and a correction matrix is estimated based on the plurality of beam vectors. The initial calibration matrix and the correction matrix are combined in order to estimate a refined radar calibration matrix which is utilized as calibration matrix when applying the radar sensor.