A flow meter has fluid flow through a measurement path in a measuring tube with a main channel and at least one secondary channel. A signal input device introduces a measurement input signal into the fluid and a signal detection device detects the measurement input signal and/or a response signal induced by the measurement input signal. For a predetermined fluid, the main and secondary channels with a first total throughput of the fluid per unit time and with a second total throughput of the fluid per unit time, which is greater than the first total throughput of the fluid per unit time. The ratio of the throughput through all the secondary channels to the throughput through the main channel is greater in the second total throughput than in the first total throughput of the fluid per unit time.