Device for measuring the amount of flowing liquid, which device is composed of a liquid recipient (2) divided into two chambers (4, 5), an external valve (6), a flexible tube (7) and a calculation unit (10) and is characterized in that the liquid recipient (2) has two capacitive sensors (11, 12) installed in the external wall thereof, which sensors measure the liquid level in each chamber. The measurement method is characterized in that the volume of liquid V contained in the first chamber (4) of volume R 1 is measured with an interval T 1 using the first capacitive sensor (11), and, when V ‰¥ R 1 - µ, it is determined whether the liquid is allowed to pass to the second chamber (5), where the volume is measured using the second capacitive sensor (12), or the external valve (6) is opened and the measurement process is restarted.
