Abstract: This invention relates to a device for measuring the level and the density of a liquid contained in a tank. The device comprises a first pressure-sensitive transmitter close to the bottom of the tank, and two pressure-sensitive transmitters arranged on fixed different levels below the highest permitted liquid level, which two transmitters are compensated for variations of the gas or air pressure in the space above the liquid level. The measurement data from the first transmitter is indicated by a first indicator and the difference of the measurement data from the second and third transmitter is indicated by a second indicator.