Physics of Interaction · principle
Tesler's Law
Playable Play this law (~3 min)or keep reading below ↓
Every process has a certain amount of complexity that cannot be removed — it can only be moved. The 'law of conservation of complexity' asks who absorbs it: the user or the designer/system. Good products take on the hard, fiddly work internally so the person is left with the simplest possible experience.
Where it comes from
The law is named for Larry Tesler, a computer scientist at Xerox PARC and later Apple, who formulated it in the 1980s while thinking about how much of an application's difficulty should fall on users versus engineers. Tesler was also a champion of modeless interfaces and is often credited with popularising cut, copy, and paste — features that are themselves examples of moving complexity off the user and into the system.
Origin: Larry Tesler's 1980s work on interface complexity at Xerox PARC / Apple
In the wild
- Email 'To' fields
The app autocompletes and validates addresses — absorbing the complexity of formats and typos so you just type a name.
- Smart defaults
Sensible pre-filled values handle the common case; the system carries the decision so most users never touch it.
- Date pickers
A calendar widget absorbs the messy complexity of valid dates and formats instead of pushing it onto the user.
Further reading
Don't just read it — feel it.
Play the 3-minute game and let your own reactions prove the law.
Play the lesson