Disclosed is a method for gauging the liquid propellant tank of a spacecraft during a phase of high-thrust along an axis, the tank being thermally conductive and having a known geometry. The method includes steps of: attaching, on a wall of the tank, a heating member and at least one temperature sensor in proximity to the heating member and in a plane of interest perpendicular to the thrust axis; during the high-thrust phase, heating the wall of the tank and acquiring temperature measurements of the wall of the tank at rapid frequency; determining the instant I when the temperature measured by the sensor changes, such change indicating the presence of the liquid-gas interface in the tank in the plane of interest; and determining the volume of liquid propellant present in the tank at instant I.