What is ISO-compliant Usability?

If you want to implement usability professionally, you need to follow the ISO 9241 guidelines. But what does “ISO-compliant” actually mean - and why is it crucial for the quality of digital products?

Definition

ISO-compliant usability means that the design and evaluation of an interactive system follows the principles and requirements of the relevant parts of the ISO 9241 standard - in particular Part 11, 110 and 210.

Relevant standard parts

The three central pillars of ISO-compliant usability are:

ISO 9241-11: provides the definition and evaluation criteria of usability
ISO 9241-110: describes principles for user-friendly dialog design
ISO 9241-210: focuses on the user-centered development process

These standards are internationally recognized and are used in research, teaching, development, testing and audits.

What does ISO 9241-11 require?

According to the standard, a product is only considered fit for use if it fulfills three criteria in a concretely described context of use:

Effectiveness: Is the user goal achieved?
Beispiel: Ein Nutzer kann erfolgreich eine Steuererklärung einreichen.
Efficiency: How much effort is required for this?
Beispiel: Der Prozess dauert nur wenige Minuten und ist verständlich aufgebaut.
Satisfaction: How pleasant is the subjective experience of the process?
Beispiel: Nutzer:innen berichten von Klarheit, Vertrauen und Kontrolle.

Kontext ist entscheidend

A system can perform excellently in one usage context - and be unusable in another. Usability is never absolute, but always situation-dependent.

What does design according to ISO 9241-110 mean?

The standard describes seven ** design principles** that serve as a guideline for user-friendly interfaces - including:

Expectation conformity: Users find what they expect (e.g. “Save” at the top right).
controllability: Users retain control over processes (e.g. “Back” function).
Error tolerance: Errors must not lead to frustration, but must be detectable and correctable.
Ease of learning: Even inexperienced users can understand the system after a short time.

These principles are concretized in heuristic evaluations, style guides and design systems.

What does the process look like according to ISO 9241-210?

Part 210 of the standard requires a iterative, user-centered design process. This means:

understand the context of use - through interviews, observations or personas
derive requirements from the user’s perspective - e.g. as scenarios or task descriptions
develop design solutions - ideally collaboratively
test prototypes with users - through usability tests, walkthroughs, etc.
incorporate results into iterations - until the goals are achieved

Best Practice Example

A team develops an onboarding function for a banking app. Following contextual interviews, they create prototypes that are validated and iteratively improved in several rounds of testing with real users.

Why is ISO conformity important?

It creates transparency and traceability in UX decisions
It allows usability to be measured and documented in a standardized way
It forms the basis for legal evidence for accessibility or product liability
It promotes a common language between UX, development, QA and management

Conclusion

ISO-compliant usability is more than just good design: it is a methodologically sound, context-dependent and evaluable quality of digital systems.
For UX professionals, it is a benchmark. A process for teams. For organizations, a maturity indicator.

Take Home Message

ISO-compliant usability is not a promise - it is a proven quality feature.

Last modified: 17 June 2025