Free Apdex calculator. Compute an Application Performance Index score from satisfied, tolerating and frustrated request counts, with the threshold T explained.

The formula

Apdex = (Satisfied + Tolerating/2) / Total

Satisfied  : response time ≤ T
Tolerating : T < response time ≤ 4T
Frustrated : response time > 4T

The score runs 0–1. Its entire meaning hinges on the threshold T — set it to your real latency SLO, not a generic default, or the number is disconnected from any decision. Apdex is a useful trend metric; for diagnosis, reach for percentiles instead.

Background: understanding Apdex and why percentiles beat averages.

Discussions coming soon.

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Apdex Calculator

The formula