A method for calibrating a tool centre point of tool for an industrial robot system comprising a cross beam sensor that has a first beam and a second beam which are angled to each other with a vertex angle greater than zero and cross each other at a crossing point, including: (a) relatively moving a first part of said tool and a cross beam sensor by said industrial robot with translational motion in an orientation so that said first part of said tool respectively interrupts said first beam and said second beam of said cross beam sensor; (b) recording a first posture and a second posture of said industrial robot during the interruptions of said first beam and said second beam of said cross beam sensor by said first part of said tool; (c) relatively moving a second part of said tool and said cross beam sensor by said industrial robot with translational motion while maintaining said orientation so that said second part of said tool respectively interrupts said first beam and said second beam of said cross beam sensor; (d) recording a third posture and a fourth posture of said industrial robot during the interruptions of said first beam and said second beam of said cross beam sensor by said second part of said tool; (e) calculating the tool orientation (Ω) in consideration of said first posture, second posture, third posture and fourth posture of said industrial robot as well as said first beam direction and said second beam direction; and (f) relatively moving said tool and said cross beam sensor by said industrial robot so that said tool centre point of said tool interrupts said crossing point of said cross beam sensor in consideration of said tool orientation (Ω) and either the first and the second postures or the third and the fourth postures of said industrial robot. (a) relatively moving a first part of said tool and a cross beam sensor by said industrial robot with translational motion in an orientation so that said first part of said tool respectively interrupts said first beam and said second beam of said cross beam sensor; (b) recording a first posture and a second posture of said industrial robot during the interruptions of said first beam and said second beam of said cross beam sensor by said first part of said tool; (c) relatively moving a second part of said tool and said cross beam sensor by said industrial robot with translational motion while maintaining said orientation so that said second part of said tool respectively interrupts said first beam and said second beam of said cross beam sensor; (d) recording a third posture and a fourth posture of said industrial robot during the interruptions of said first beam and said second beam of said cross beam sensor by said second part of said tool; (e) calculating the tool orientation (Ω) in consideration of said first posture, second posture, third posture and fourth posture of said industrial robot as well as said first beam direction and said second beam direction; and (f) relatively moving said tool and said cross beam sensor by said industrial robot so that said tool centre point of said tool interrupts said crossing point of said cross beam sensor in consideration of said tool orientation (Ω) and either the first and the second postures or the third and the fourth postures of said industrial robot.