Abstract: The invention concerns a grain tank for a combine harvester with a grain tank cover which can move between a closed and an opened position, closing off the grain tank at the top in the closed position, and in the open position expanding the useful volume of the grain tank upward. A rangefinder is proposed for detecting the fill level in the grain tank, which is arranged such that it is in a position above the maximum fill level of the fill material suitable for detecting the fill level of the fill material when the grain tank cover is opened, while when the grain tank cover is closed it is covered by the latter.