Abstract. When unloading grain harvester hoppers at a standstill the emptying time has an effect on the grain harvester performance. A study has been conducted on the actual emptying time of harvester grain hoppers on various farms in Bulgaria and the actual flow rate of the unloading auger has been determined. The results obtained have been compared to the designed ones. It has been established that when unloading at a standstill the full rate of the unloading auger is not in use, but only 73.14% of it, with which the hopper emptying time is 1.4 times greater than the theoretical one.