Abstract. The quality of fixtures plays an important role in product quality during manufacturing, measuring or assembly. Finding methods for evaluating a fixture's quality, which may depend on workpiece errors, fixture errors, influences of clamping force, friction, etc., is necessary to improve the product quality. This paper proposes the indicators that are used for estimating the quality of a fixture based on workpiece localization repeatability. Here, the workpiece localization will be considered in the following different cases: (1) considering only the influence of different geometric parameters (types) of the fixture, (2) taking into account the clamping force in the different types of the fixture, (3) the influence of friction on the contacts of the workpiece-fixture. A fixture model is presented and analysed with some examples. An experimental fixture and workpiece are then used to analyse and compare with the theoretical results.