Understanding Apdex Score
How we calculate. Apdex = (satisfied + 0.5 × tolerating) ÷ total samples (0 to 1 scale). See our methodology and accuracy policy .
Real-world scenario: A typical Apdex Score case uses satisfied samples 8000 and tolerating samples 1500. Enter the same figures below to reproduce the worked path.
What is Apdex Score?
Apdex turns latency distributions into a 0–1 score using a threshold T you define (satisfied ≤ T, tolerating ≤ 4T, else frustrated).
- Pick T carefully (e.g. 0.5s for APIs, higher for pages)
- 1.00 is perfect; many teams target ≥ 0.85–0.94
- Frustrated samples still sit in the denominator
The Formula
Worked Example
Common Use Cases
- Executive dashboards: one UX-friendly number
- Release gates: minimum Apdex targets
- Endpoint ranking: find painful APIs
Pro Tips
- Publish T with the score
- Do not mix page and API samples
- Track trend, not vanity peaks
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Apdex Score figures are educational performance-testing aids—not contractual capacity guarantees. Validate with calibrated load tools and production telemetry.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
The worked example for apdex score calculator was verified with the calculator form on this page—enter the same values to confirm the result.
When to use this calculator
- Use this page when your wording matches apdex score calculator and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about apdex score calculator? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this apdex score calculator calculator?
For apdex score calculator, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for apdex score calculator—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking apdex score calculator, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For performance and quality engineering context, consult:
- ISTQB — performance testing syllabus topics
- W3C Navigation Timing — browser performance timing
- CMG / capacity forums — capacity and performance practice communities