Calculate how long it will take to process the records on your queue/topic.
In general terms, throughput is the rate at which something is processed, for example, Bob takes 10 minutes to read a book page, that's his throughput.
RPM is a unit to measure throughput, it means Requests Per Minute, with this metric you can understand how much time is necessary to do something and eventually calculate the required throughput to process some other volume.