A system for measuring flow rate with at least a first and a second flow meter provides a flow-rate measurement system which easily allows self-monitoring. This result is achieved by the system in that the first flow meter and the second flow meter differ from one another and/or have different orientations for the flow rate measurement, and each have an evaluation unit which produces data from the flow rate measurement. Furthermore, there is a monitoring device which is connected to the evaluation units such that the monitoring device acquires data produced by the evaluation units, and which is made such that it produces at least one comparison result from a comparison of the data produced by the evaluation units and signals at least the occurrence of a fault state which is associated with at least one comparison result.