We introduce two throughput metrics referred to as flow-and time-sampled through-puts. The former gives the throughput statistics of an arbitrary flow while the latter weights these throughput statistics by the flow durations. Under fair sharing assumptions, the latter is shown to coincide with the steady-state instantaneous throughput weighted by the number of flows, which provides a useful means to measure and estimate it. We give some generic properties satisfied by both metrics and illustrate their difference on a few examples.