Tesler’s Law
Some task complexity is irreducible, so design determines whether the system, the user, or an organization carries that work.
Direct explanation
What it means
Automation and defaults can move complexity away from the immediate interface, but it reappears in rules, exceptions, maintenance, explanation, or reduced user control.
A visually simple screen may impose hidden labor on users or support staff. The heuristic encourages teams to account for complexity instead of pretending it vanished.
Research anchor: Larry Tesler
Research and interpretation
What the research found
Tesler articulated the principle from professional practice rather than a controlled scientific program.
The idea aligns with automation tradeoffs, distributed cognition, and total-cost reasoning, but has no fixed quantitative conservation equation.
Popular advice versus careful use
Common shorthand: Complexity is fixed, so teams only choose whether users or engineers suffer.
Trace necessary and accidental work across the whole service, then place each part where it can be handled accurately, transparently, and fairly.
How designers apply it
- 01
Calculate a tax field from known data while letting users inspect and correct inputs.
- 02
Use system-managed permission templates with explicit exceptions.
- 03
Move formatting work into a design-system component rather than every product team.
Original UI examples
mobile finance
Expense report
The system extracts receipt data and highlights uncertainty for review.
Routine transcription moves to the product while judgment stays with the submitter.
desktop enterprise
Role administration
Templates cover common access patterns and a diff reveals custom exceptions.
Admins avoid repetitive setup without losing a model of the resulting permissions.
AI-assisted form completion
Less effective
Hide all inferred answers to make the form one click.
Better fit
Prefill with provenance, confidence, editable values, and a consequential review.
Automation that cannot be inspected often creates downstream correction complexity.
Limits and failure modes
Complexity can sometimes be eliminated through reframing, policy change, or better technology; the total is not literally constant.
Common mistakes
- Equating fewer visible fields with lower total complexity.
- Moving work to users because implementation is difficult.
When it should not dominate
- To claim a current architecture is inevitably complex.
- To automate value judgments that require informed human control.
Responsible use
Accessibility
Do not shift complexity into inaccessible exception flows; automated assistance must remain understandable, operable, and correctable through assistive technology.
On mobile: Let the system handle repetitive input but preserve a compact, readable review of assumptions and results.
Ethics and context
Account for labor transferred to customers, moderators, support staff, and marginalized users, not only engineering effort.
On desktop: Expose advanced exception handling without making it the default path for routine work.
Designer checklist
- Map who performs each mental and operational step.
- Automate reliable repetition and expose uncertainty.
- Test exception, correction, and support burden.
Check your understanding
Which statement applies Tesler’s Law most carefully?
Practice and continue learning
See ideas in real interfaces
These external interfaces are editorial references, not examples created to demonstrate this principle.
Sources and further reading
- 01Open source
Larry Tesler's Law of Conservation of Complexity
Larry Tesler · Larry Tesler
Official documentation · primary or original source
- 02Open source
The Design of Everyday Things: Revised and Expanded
Donald A. Norman · 2013 · Basic Books
Book · primary or original source
Continue the graph
Related principles
theory
Cognitive Load
Cognitive load describes demands placed on limited working-memory resources while a person learns or performs a task.
model
Intrinsic Cognitive Load
Intrinsic cognitive load is the working-memory demand created by interacting elements that are inherent to what must be understood or performed.
usability heuristic
Progressive Disclosure
Progressive disclosure presents the information and controls needed now, then reveals additional detail when the user asks or the task reaches it.