The German national metrology institute, the Physikalisch-Technische Bundesanstalt (PTB), has developed a novel calibration method for gear artefacts. This reduces the current calibration uncertainty of gear standards, which is an essential step towards meeting the rising quality demands of the gear manufacturing industry. The measurement setup is based on a coordinate measuring machine (CMM) equipped with a high-precision rotary table. The key element of the novel gear measuring device is a tracking interferometer (TI) for reading the distance information. This information is combined with the reading of the coordinate measuring machine line scales in order to reduce the overall measurement uncertainty. If an optimized measurement strategy is applied, the measurement results are almost achieved with laser interferometer accuracy. First simulations and measurement results for an involute profile artefact are presented and discussed.