Reading a scaling report
When a load test finishes, open its report to see how the target behaved as the load rose. This page walks through each metric and what it tells you.
Response-time distribution
Section titled “Response-time distribution”How long requests took to complete, shown as a distribution rather than a single number. A tight distribution means consistent performance; a long tail means some requests were much slower than the rest — often the first sign of strain.
Latency percentiles
Section titled “Latency percentiles”The same timing data summarized as percentiles:
- p50 — the median. Half of requests were faster than this.
- p90 — nine in ten requests were faster than this.
- p99 — your slowest one percent. This is what your worst-affected users actually experienced.
Watch the gap between p50 and p99. A low median with a high p99 means most users are fine but a meaningful minority are seeing painful delays.
Error rates by status code
Section titled “Error rates by status code”The proportion of responses that failed, broken down by HTTP status. This tells
you not just how many requests failed but how — for example a rise in 5xx
errors points to the server falling over under load, while 4xx errors may point
to throttling or auth limits being hit.
Throughput
Section titled “Throughput”How many requests the target successfully served per unit of time. Throughput that climbs with load and then flattens (or drops) marks the point where the target stops keeping up.
How response codes change as load rises
Section titled “How response codes change as load rises”A view of how the mix of response codes shifts as the virtual-user count increases. This is the most direct read on capacity: the virtual-user level where successful responses give way to errors is, in practice, your ceiling.
Interpreting the results together
Section titled “Interpreting the results together”- Healthy under load — response times stay flat, errors stay near zero, and throughput tracks the load. You have headroom.
- Approaching the limit — p99 climbs while p50 stays low, throughput flattens. You’re nearing capacity.
- Past the limit — error rates climb (especially
5xx) and throughput falls. The target can’t serve the offered load.
Where to go next
Section titled “Where to go next”- Running a load test — adjust the load and run again to confirm a fix or find the next limit.