Calculated on the HTTP requests sent out each second. Because the measurement is per second; but, the granularity of the graph is not 1 second, it is possible to have fractions of hits per second. If you change the granularity to 1 second, then only whole hits per second will be recorded.

The ''Hits per second'' graph is calculated depending on the HTTP requests sent out each second. If there are no HTTP requests sent for some time, then a request is sent out, the hits per seconds is computed for the entire interval since the last hit was received.

Example: Say you have only one HTTP Request that is sent at the fifth second of a scenario before which there are no requests sent, the hits per second would be recorded as 0.2 hits per second (HPS) for each of the first 5 seconds. If, after that, you have 1 hit every 1 second for the next 5 seconds they would be displayed as 1 HPS for the next 5 seconds in the HPS graph.

The Average HPS however will be different as follows:
2/6 = 0.33 HPS for the 6th second
4/8 = 0.50 HPS for the 8th second
6/10= 0.60 HPS for the 10th second

If, after that, there are no HTTP requests sent for the next 4 seconds and ONLY one HTTP request is sent at the fifth second, the HPS would be 0.2 for the last 5 seconds.