15 must-know UX laws for creating experiences users love

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

In simple words, a user has a "distance" they need to travel in order to use a specific button and a range of "obstacles" along the way. Originating from a study on human motor behavior, Fitt's Law helps calculate this distance, find shortcuts, and optimize the UX.

Mathematical expression:

T = a + b × log₂(1 + D/W)

where T is the time to move to the target, D is the distance, and W is the target width.

Best practice: Make interactive elements larger and closer — that way, users must put less effort into actually making out each tiny thing and reaching for functions. That is especially important for interactive elements and interactions in mobile and touch UIs.

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

It's that simple — the more UI functions there are, the more time a user needs to actually point or tap at something specific. This law comes from a big set of experiments on human choice and reaction time, putting minimalism and conciseness of UX above all else.

Math expression:

T = b × log₂(n + 1)

where T is the time to make a decision, b is a constant, and n is the number of choices.

Best practice: Minimize the range of simultaneous choices a user sees on the screen; hide ranged options into handy menus; segment complicated data into bits; remove clicks from processes like checkout.

People tend to work harder as they get closer to achieving a goal.

This psychological effect is proven by the efficiency of loyalty programs and last-chance product offers. Users become much more engaged when they get closer to their goal, especially as these goals become more realistic (e.g., a user sees the completion bar of their loyalty incentive).

Best practice: Use visual indicators like progress bars and checklists to motivate users to complete tasks. Create even more sense of progress by making the steps like account creation reflect in the profile completion status.

Users always browse many other sites — your site shouldn't stand out too much.

Jakob Nielsen's research on user behavior and familiarity proves that it's not all about the quality of UI/UX. Users prefer familiar stuff over something that must be figured out anew. That is backed by another big psychological phenomenon called the mere-exposure effect.

Best practice: Go by established design conventions. Place elements where users expect to see them. You don't have to reinvent the wheel to keep a UI/UX design relevant and in line with user expectations.

The average person can hold 7 +/- 2 items in their working memory.

George A. Miller's 1956 study on cognitive capacity explains that the human brain can simultaneously manage about 5 to 9 discrete pieces of information. Minimizing them can help grab users' attention more efficiently.

Best practice: Deliver information in smaller, digestible chunks and offer feature-by-feature so as not to overwhelm users with info bombards.

People remember incomplete tasks better than completed ones.

Unfinished tasks create cognitive tension — it's like you can't shake off pressing thoughts on that upcoming deadline, whatever you do. Once you complete the task, however, your memory frees up space.

Best practice: Stimulate users' memory and keep them engaged by highlighting actions that are pending actions or require completion.

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

Going a bit beyond UI/UX laws only, the 80/20 rule explains a very important notion — there are a bunch of essential tasks, features, or design elements that define the entire level of UI/UX. This means that you should focus on them and maximize them before adding more.

Best practice: Focus on the essential features that deliver the bulk of value (e.g., prioritize user persona research and outsource AR/VR integrations).

Items that stand out are more likely to be remembered.

Also called the isolation effect — some surrounding contrast always makes an element more memorable. A well-contrasted element literally grabs the eye.

Best practice: Make certain elements stand out against the screen backdrop to grab and hold onto user attention.

Users tend to perceive aesthetically rich designs with more confidence.

Building an aesthetically pleasing UI/UX design gives you a chance to tweak a user's perception of usability to your advantage. Visually rich, polished designs instill a sense of confidence: "It looks great. I should probably try it out."

Best practice: Invest in polished, eye-pleasing UI/UX designs. Use dynamic elements, like animation, and interactive features, like sliders and maps.

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

In psychology, there is the primacy effect (remembrance of first items) and recency effect (remembrance of last items). This knowledge should help you position UI/UX elements accordingly.

Best practice: Place important information, CTAs, or functionalities at the beginning or end of menus and lists.

Information should be presented gradually so as not to overwhelm the user.

One of the go-to UX rules is to present only essential information to the user at first, revealing more detailed content upon user request. In this way, you make complex details easily digestible and prevent information overload.

Best practice: Show only what's essential first, then let users decide whether to dive deeper. Keep the UI/UX uncluttered.

People perceive complex images in the simplest way possible.

The Law of Prägnanz comes out of the underlying principles of Gestalt psychology. AKA the Law of Simplicity states that the human mind favors organized, symmetrical, and simple structures. Hence, there is overwhelming minimalism in the most popular designs in this world.

Best practice: Instead of coming up with complex UI/UX visuals and thinking about how to simplify them, go for straightforward, easily perceivable shapes and images.

Every application has an inherent amount of complexity that cannot be reduced.

It's also known as the law of conservation of complexity, where some complexity must be managed, not eliminated. The unavoidable complexity usually involves processes that require manual input (like profile registration), personalization settings, etc.

Best practice: Instead of throwing away certain steps and actions, automate them (e.g., enable auto-filling for the user registration process).

A well-designed interface can feel "magical" when it anticipates user needs seamlessly.

Sealing up our list of the main UX design rules, the Law of Magic doubles down on the intuitiveness and magical feel of your UI/UX. It is not uncommon for users to feel like they're "in the zone" when the design is filled with engaging and simply delightful interactions.

Best practice: Instant responses to user input, functions that predict user needs, micro-interactions (like mini-games in place of error screens), and advanced feature interactions can all help create these magical moments.