A programmable hair trimming system has a hair trimming device including a receiving element configured to receive an electromagnetic field and at least one source element having an electromagnetic field source. The hair cutting length of the hair trimming device is adjustable, and the at least one source element is external to the hair trimming device and arranged to be placed in a fixed relationship to the head of a person. The hair trimming system is arranged to detect, by an electromagnetic tracking system, the position of the hair trimming device in relation to the at least one source element. Further the hair trimming system relates this position to a previously generated hair length profile data regarding the desired hair trimming length at various positions. Based on the desired hair trimming length at the sensed position, the trimmer cutting length is automatically and dynamically adjusted.