Apdex Score Calculator

Work out apdex score instantly with clear inputs, formula shown and shareable results.

About Apdex Score Calculator

Apdex condenses a latency distribution into one number between 0 and 1 by counting satisfied requests fully, tolerating requests at half, and frustrated requests not at all. The frustration boundary is fixed at four times the satisfaction threshold. Its value is comparability across services; its weakness is that the score depends entirely on the threshold you chose, so it must always be quoted with T.

Formula

Apdex

Apdex(T) = (satisfied + tolerating / 2) / total; tolerating = requests between T and 4T; frustrated = requests above 4T

Worked example

With the default values below, Apdex Score Calculator returns Apdex score of 0.9274. Change any input above and every figure here is recalculated in your browser.

Inputs used

Satisfied requests (under T)minimum 0: 84,000
Tolerating requests (T to 4T)minimum 0: 9,500
Frustrated requests (over 4T)minimum 0: 2,200
Satisfaction threshold Tminimum 1 ms: 500 ms

Results

Apdex score: 0.9274
Apdex rating: Good
Share of frustrated requests: 2.30%
Frustration threshold (4T): 2,000 ms

Step by step

1Values used
2Apdex
3Apdex score= 0.9274
4Apdex rating= Good
5Share of frustrated requests= 2.30
6Frustration threshold (4T)= 2,000 ms

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How should T be chosen?

From user expectation for the interaction, not from current performance. Setting T to your existing p90 guarantees a flattering score that never improves.

Is Apdex still relevant?

It is less fashionable than SLO-based measurement, which expresses the same idea with an explicit target and error budget. Apdex remains useful as a single trend line for stakeholders.