In the context of stringed musical instruments, "mensur" refers to the vibrating string length (usually expressed in centimeters). The mensur is the distance between the inside edge of the nut (the point where the strings start at the top of the fingerboard) and the inside edge of the bridge of the instrument. This measurement is crucial because it affects the pitch or frequency of the notes produced when the strings are played.

The mensur — or vibrating string length — can vary from one instrument to another and may also be adjusted on some instruments to achieve different tunings or tonal qualities. Instruments with longer string lengths generally produce lower-pitched notes, while those with shorter string lengths produce higher-pitched notes.

Musicians and luthiers pay close attention to the mensur when building and setting up instruments to ensure proper intonation and tonal characteristics.