Plastic gears are mostly used in the textile, food, and automotive industries due to their silent operation, corrosion resistance, and light and cheap advantages. Plastic gears are generally manufactured by injection molding or hobbing methods. The excess costs of the molds used to produce parts in injection molding and the problems of wastes that occur during production in hobbing lead companies to additive manufacturing, which is an alternative application. In the additive manufacturing method, the desired amount of product is produced without the problem of waste. In this study, the wear resistance of plastic spur gears produced by the Fused Deposition Modeling (FDM) method was determined theoretically. In order to determine the service life of gears, wear tests were carried out in the Forschungsstelle fur Zahnrader und Getriebebau (FZG) type test device at the same load and rotational speeds. polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PETG) thermoplastic polymer materials were used in the production of gears. When the gears rotate at the same load and rotational speeds, the most wear was observed in ABS, PLA, and PETG at the theoretically calculated wear depths. PETG is the most resistant material in terms of wear.