Laws of UX

A collection of key rules that UX designers should consider when designing user interfaces.

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Heuristics

A heuristic is a simple, experience-based rule used to make decisions or solve problems quickly.
In UX, heuristics are often applied to evaluate the usability of interfaces.

Aesthetic-Usability Effect

Users often perceive aesthetically pleasing design as more usable.

Fitts’s Law

The time to acquire a target is a function of the distance to and size of the target.

Goal Gradient Effect

People are more motivated to complete a task the closer they are to finishing it.

Hick’s Law

The time it takes to make a decision increases with the number and complexity of choices.

Jakob’s Law

Users prefer your site to work the same way as other sites they already know.

Miller’s Law

The average person can keep 7 (plus or minus 2) items in their working memory.

Paradox of the Active User

The more users engage with a site, the more likely they are to return.

Parkinson’s Law

Work expands to fill the time available for its completion.

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Principles

Principles are high-level ideas used to inform the design of user interfaces.

Doherty Threshold

Productivity soars when computer and user interactions occur within 400ms, minimizing wait times.

Occam’s Razor

Among competing hypotheses, the one with the fewest assumptions should be selected.

Pareto Principle

Roughly 80% of effects come from 20% of causes.

Postel’s Law

Be liberal in what you accept, and conservative in what you send.

Tesler’s Law

There is a certain amount of complexity in systems that cannot be reduced.

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Gestalt Principles

Gestalt principles explain how humans perceive the world visually.

Law of Common Region

Elements sharing an area with a clearly defined boundary are perceived as grouped.

Law of Proximity

Objects near each other are perceived as related.

Law of Prägnanz

People interpret complex images as the simplest form possible.

Law of Similarity

The human eye groups similar elements together naturally.

Law of Uniform Connectedness

Visually connected elements are perceived as more related than disconnected ones.

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Cognitive Biases

Cognitive biases are systematic deviations from rational judgment.

Peak-End Rule

People judge experiences based on the peak moment and the end, not the overall average.

Serial Position Effect

Users best remember the first and last items in a sequence.

Von Restorff Effect

When multiple similar objects are present, the one that differs most is remembered.

Zeigarnik Effect

People remember interrupted or uncompleted tasks better than completed ones.

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Conclusion

Understanding and applying these UX laws can greatly enhance user experiences.
By aligning designs with human psychology and behavior patterns, you create products that feel intuitive, engaging, and easy to use.