Abstract: A level gauge (1) for measuring the amount of liquid in a tank, such as a ground tank (19) containing fuel (21, is disclosed. The level gauge (10 comprises a probe (2) having a pressure sensor based on registration of hydrostatic pressure differential between the liquid and the tank atmosphere. The probe (2) is submersed in the liquid and is located adjacent to the bottom of the tank. The probe (2) is in tank atmospheric communication with an air trap (4), which is located in the tank atmosphere above the surface of the body of liquid.