A medical instrument identification setup, comprising - a sensor carrier (100, 202, 302, 510), configured to be removably arranged in a lumen (308, 504) of a medical instrument, the sensor carrier (1 00, 202, 302, 510) having at least two localizers (106, 108, 110, 310, 312; 512, 514), the localizers each being configured for providing a sensor signal representing position and orientation of the respective localizer, - a position detection system, configured for determining position and orientation of the at least two localizers (106, 108, 110, 310, 312; 512, 514) in a position detection system's coordinate system from received sensor signals, - a calibration device (204, 306, 522), configured such that its position and orientation in the position detection system's coordinate system can be determined by the position detection system, - a calibration unit, configured for calibrating a medical instrument with the sensor carrier (100, 202, 302, 510) arranged in its lumen (308, 504) by calculating a distance between the medical instrument's tip and at least one of the two localizers (106, 108, 110, 310, 312; 512, 514) based on the position and orientation of the calibration device (204, 306, 522) and the position and orientation of at least one of the two localizers (106, 108, 110, 310, 312; 512, 514) determined by the position detection system, and - a medical instrument identification unit, configured for determining a length of the medical instrument's lumen (308, 504) at least from the calculated distance and for using the determined length of the lumen (308, 504) for identifying the medical instrument. - a sensor carrier (100, 202, 302, 510), configured to be removably arranged in a lumen (308, 504) of a medical instrument, the sensor carrier (1 00, 202, 302, 510) having at least two localizers (106, 108, 110, 310, 312; 512, 514), the localizers each being configured for providing a sensor signal representing position and orientation of the respective localizer, - a position detection system, configured for determining position and orientation of the at least two localizers (106, 108, 110, 310, 312; 512, 514) in a position detection system's coordinate system from received sensor signals, - a calibration device (204, 306, 522), configured such that its position and orientation in the position detection system's coordinate system can be determined by the position detection system, - a calibration unit, configured for calibrating a medical instrument with the sensor carrier (100, 202, 302, 510) arranged in its lumen (308, 504) by calculating a distance between the medical instrument's tip and at least one of the two localizers (106, 108, 110, 310, 312; 512, 514) based on the position and orientation of the calibration device (204, 306, 522) and the position and orientation of at least one of the two localizers (106, 108, 110, 310, 312; 512, 514) determined by the position detection system, and - a medical instrument identification unit, configured for determining a length of the medical instrument's lumen (308, 504) at least from the calculated distance and for using the determined length of the lumen (308, 504) for identifying the medical instrument.