The mass of a fluid flowing through a flow rate meter at a temperature which fluctuates in a given temperature range is determined by driving an exciter magnet system through the fluid with an exact correlation between the fluid volume flowing there through and the movement path covered by the exciter magnet system, producing a measurement voltage pulse after each passage through a movement path corresponding to a unit volume of the fluid by means of a Wiegand wire and a coil surrounding same, at each measurement time charging a first energy storage means by electric energy contained in each measurement voltage pulse, and using same as operating energy for measurement of the instantaneous temperature of the fluid, producing a temperature value as an integral multiple of the smallest temperature measurement unit to be resolved and an integral count value including said temperature value, and adding same to a sum contained in a non-volatile storage means from the precedingly ascertained count values for forming an ongoing sum in the non-volatile storage means and passing same to a processor which can be supplied with external energy and which calculates therefrom the temperature-corrected delivery volume of the fluid.