A method of determining the quantity of milk extracted by a milking installation from one cow consists of producing a continuous flow of milk (28) from one cow and making, from that flow, separate doses of milk (28). The production of separate doses of milk (28) in a device for implementation of said method is effected by making separate doses of milk (28) corresponding to a preset flow rate of milk (28) by means of a milk flow rate transmitter (24) located in a receiving chamber (22) of a milk counter (1), a correction being thus introduced into the process of production of separate milk doses by means of a pick-up (15) for selecting separate milk doses, said correction characterizing the dynamic error. Then, from the separate doses of milk (28), optimal doses of milk (28) are determined with due consideration of the qualities of the milk (28) and of the maximum sensitivity of the counter (1), by means of an optimal milk dose pick-up (33) located in the outlet chamber (23) of the counter (1), a correction being thus introduced into the process of determining the optimal doses of milk (28) by means of a pick-up (16) for summing the optimal milk doses, said correction characterizing the static error. The optimal doses of the milk (28) are then summed together by means of a computing unit (19).