Procedure for measuring the level in a vessel which contains a quantity of a first product and/or a quantity of a second product, wherein the first product has a lower specific gravity than the second product, and the two products (3, 5) have different dielectric constants (ε), wherein in said - an electromagnetic signal is transmitted into the vessel, - a reflection takes place at at least one medium boundary generated by the products (3, 5) contained in the vessel, wherein a part (Rx, Ry) of the signal is reflected during said reflection, and - a time-of-flight (Tx, Ty), which depends on the position of the medium boundary triggering the reflection, is measured for each reflected part (Rx, Ry), said time-of-flight being the time this part (Rx, Ry) of the signal needs to travel the distance to this medium boundary and back, - a capacitance, which depends on the quantities of the products (3, 5) located in the vessel, is measured between a capacitance probe and a reference electrode, and - on the basis of the capacitance and the times-of-flight (Tx, Ty) measured for each of the products (3, 5) in the vessel, a position is determined that corresponds to the position that the surface of the individual product (3, 5) adopts due to the quantity of the first product contained in the vessel and the quantity of the second product contained in the vessel if the total quantity of each product (3, 5) in the vessel forms a single layer containing only this product (3, 5), wherein in the case that it was only possible to determine one time of flight (Tx), - a hypothesis is put forward concerning the medium boundary at which the reflection determining the time-of-flight (Tx) took place, - the position that the surface of the individual product (3, 5) adopts due to the quantity of the first product contained in the vessel and the quantity of the second product contained in the vessel if the total quantity of each product (3, 5) in the vessel forms a single layer containing only this product (3, 5) is determined for each product (3, 5) found in the vessel using the measured time-of-flight (Tx), the measured capacitance and the hypothesis, - the correctness of the positions determined on the basis of the hypothesis are checked based on the physical boundary conditions, and - this procedure is repeated with a modified hypothesis if the check has a contradictory result. - an electromagnetic signal is transmitted into the vessel, - a reflection takes place at at least one medium boundary generated by the products (3, 5) contained in the vessel, wherein a part (Rx, Ry) of the signal is reflected during said reflection, and - a time-of-flight (Tx, Ty), which depends on the position of the medium boundary triggering the reflection, is measured for each reflected part (Rx, Ry), said time-of-flight being the time this part (Rx, Ry) of the signal needs to travel the distance to this medium boundary and back, - a capacitance, which depends on the quantities of the products (3, 5) located in the vessel, is measured between a capacitance probe and a reference electrode, and - on the basis of the capacitance and the times-of-flight (Tx, Ty) measured for each of the products (3, 5) in the vessel, a position is determined that corresponds to the position that the surface of the individual product (3, 5) adopts due to the quantity of the first product contained in the vessel and the quantity of the second product contained in the vessel if the total quantity of each product (3, 5) in the vessel forms a single layer containing only this product (3, 5), wherein in the case that it was only possible to determine one time of flight (Tx), - a hypothesis is put forward concerning the medium boundary at which the reflection determining the time-of-flight (Tx) took place, - the position that the surface of the individual product (3, 5) adopts due to the quantity of the first product contained in the vessel and the quantity of the second product contained in the vessel if the total quantity of each product (3, 5) in the vessel forms a single layer containing only this product (3, 5) is determined for each product (3, 5) found in the vessel using the measured time-of-flight (Tx), the measured capacitance and the hypothesis, - the correctness of the positions determined on the basis of the hypothesis are checked based on the physical boundary conditions, and - this procedure is repeated with a modified hypothesis if the check has a contradictory result.