Glossary · p95 latencyAlso called 95th percentile latency, tail latencyChecked 27 September 2026
What does p95 latency mean when a vendor quotes it?
p95 latency is the time the slowest one in twenty requests takes. Averages hide those: a system that answers in half a second most of the time and eight seconds occasionally has a fine average and an unusable feel. The tail is what users remember, and it is what decides whether they keep the habit.
In one lineThe slowest 1 in 20. Averages hide exactly what users notice.
Why it matters to you
The number is only meaningful with three things attached: what was being measured, under what load, and on what date. A p95 from a laptop on office wifi with one user is not a number about production.
It also has to be measured, because a feeling is not a percentile. OCTYN publishes Mooney's voice time as under five seconds end to end, and says plainly that it is a demonstrated wall-clock time from screen recordings on a Samsung S23 over a live network, not a p95, because per-stage timing is not instrumented in the app. Instrumenting it is the first thing that project's own write-up says it would do differently.
If a vendor quotes you a p95 and cannot say what date it was captured on, it is a feeling with a decimal point.
If a proposal used this word and did not explain it, ask us.
The first conversation is with the people who would build it. If there is a fit, the Consult comes next.