Abstract: The invention relates to a one-dimensional calibration standard for coordinate measuring devices, especially for optical coordinate measuring devices, so-called laser trackers that are provided with a rod-shaped calibration device. The inventive device is characterized in that the rod-shaped calibration device consists of a single material having a thermal expansion coefficient of <5×10−6K−1 and that the rod-shaped calibration device is provided with at least two bores at predetermined calibrated intervals into which the reflective devices of the optical measuring device or the balls used for the calibration of scanning coordinate measuring systems can be exactly and reproducibly inserted and withdrawn in order to calibrate the coordinate measuring device.