The invention relates to a length measuring device with a vernier caliper, a hollow profile, on which the vernier caliper is displaceably mounted externally so that it is capable of being brought into contact with an object to be measured in terms of its length, an inner slide, which is displaceably mounted inside the hollow profile, a magnet arrangement, which couples the vernier caliper and inner slide magnetically, so that the inner slide follows every movement of the vernier caliper along the hollow profile, a measuring means for measuring the position of the inner slide along the hollow profile, and a display, visible in the surrounding space of the hollow profile, of the length determined by the measuring means in accordance with the measured position of the inner slide.
