Tesler’s Law, also known as The Law of Conservation of Complexity, states that for any system there is a certain amount of complexity which cannot be reduced.


  1. All processes have a core of complexity that cannot be designed away and therefore must be assumed by either the system or the user.
  2. Ensure as much as possible of the burden is lifted from users by dealing with inherent complexity during design and development.
  3. Remember to not build products and services for an idealized, rational user, because people don’t always behave rationally in real life.
  4. Make guidance accessible and fit within the context of use so that it can help these active new users, no matter what path they choose to take (e.g., tooltips with helpful information).


While working for Xerox PARC in the mid-1980s, Larry Tesler realized that the way users interact with applications was just as important as the application itself. The book Designing for Interaction by Dan Saffer, includes an interview with Larry Tesler that describes the law of conservation of complexity. The interview is popular among user experience and interaction designers. Larry Tesler argues that, in most cases, an engineer should spend an extra week reducing the complexity of an application versus making millions of users spend an extra minute using the program because of the extra complexity. However, Bruce Tognazzini proposes that people resist reductions to the amount of complexity in their lives. Thus, when an application is simplified, users begin attempting more complex tasks.


Further Reading

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