ISO 9241-11 Simply Explained
The ISO 9241-11 standard describes when a product is considered usable - and which criteria are decisive. It forms the basis for many usability tests and UX standards.
Definition
Usability is the extent to which a product can be used by specific users in a specific context of use in order to achieve defined goals effectively, efficiently and satisfactorily.
What does “usability” mean?
ISO 9241-11 defines three central quality characteristics that can be used to assess the usability of a product:
Effectiveness
Users achieve their goal correctly and completely.
Example: An application form is filled corretly and submitted successfully.
Efficiency
The effort required to achieve the goal is appropriate - measured in terms of time, clicks or cognitive load.
Example: The form is structured in a logical way, errors are prevented, inputs are completed automatically.
Satisfaction
The use is subjectively experienced as positive - for example through clarity, trust or aesthetic design.
Example: Using the app feels modern, intuitive and relaxed.
Context is Crucial
A central concept of the standard is the ** context of use** - i.e. the specific situation in which a product is used. ISO 9241-11 emphasizes that usability can never be evaluated in isolation from the context of use. The decisive factors are
- The users: What skills, expectations or limitations do they bring with them?
- The tasks: What is to be achieved with the system - and how complex are the processes?
- The environment: Is work mobile or at a desk? Is there time pressure, distraction or special equipment?
Important
There is no universal usability - it always depends on the specific context of use.
Why is ISO 9241-11 important?
The standard is practical and connectable: it helps to measure usability in a targeted manner, to communicate it in a comprehensible way and to improve it systematically. Its three criteria - effectiveness, efficiency and satisfaction - are used internationally in usability research and product development.
It serves as a basis for UX tests, certifications, checklists and scientific evaluations.
Conclusion
ISO 9241-11 provides a clear, easy-to-use model for testing products for their suitability for use - regardless of whether it is an app, a website or an industrial control system.
If you want good usability, you not only need a sense of design, but also a systematic basis - and that is exactly what this standard offers.
Merksatz
Effective. Efficient. Satisfactory.
This is usability according to ISO 9241-11.
Last modified: 17 June 2025