The invention relates to a biogas measuring device comprising a bioreactor (9); a gas volume measuring appliance (2) which is connected to the bioreactor (9) in a communicating manner by means of a gas line (11) for biogas; a stirring machine (10) guided in the bioreactor in a gas-tight manner, and a measurement, control and evaluation unit for controlling the biogas measuring device and determining the gas volume (V) produced in the bioreactor according to gas volumes (ΔV) of consecutive measuring cycles, measured by means of the gas volume measuring appliance (2). The inventive biogas measuring device is characterized in that the bioreactor (9) is outwardly sealed in a gas-tight manner in such a way that all gas volumes produced in the bioreactor (9) can be recorded by the measuring chamber (3) of the gas volume measuring appliance (2); a cooling element is provided on the gas line (11) for the biogas; and the measurement, control and evaluation unit is used, in each measuring cycle, to introduce a gas quantity into the measuring chamber (3) by opening the gas inlet valve (12) until a defined threshold gas pressure is reached, to close the gas inlet valve (12) when a defined threshold gas pressure is reached, to measure the temperature (Ti) in the measuring chamber (3), to open the gas outlet valve (14) for a relief time, and to close the gas outlet valve (14), and to control the biogas measuring device, in such a way that the cooling element is controlled in order to reduce the water vapor concentration in the biogas by condensation, and the measured gas volume (ΔV) of a measuring cycle is standardized to standard conditions.