Predicting the creep behaviour of geosynthetics is very important for determining the design life of geosynthetic based structures. In this paper, geogrids and geotextiles made of two major types of synthetic polymer namely, polyester and polypropylene were investigated for accelerated creep test. In short-term measurements, creep was accelerated by temperature in equal steps. As a result of the analysis, predicted creep curves for up to 30 years of design life were obtained by the stepped isothermal method. The predicted creep deformation for a period of 30 years has been analyzed. The geogrid samples made of polyester showed better creep resistance compared to polypropylene geogrids. Geosynthetic materials made of polyester are more suitable for various loaded applications as a reinforcement function.