The Laws Every UI/UX Designer Should Follow

Great design doesn’t happen by accident. Behind every intuitive interface and seamless user experience lies a set of well-established principles — often referred to as “laws” — that have been shaped by decades of research in psychology, cognitive science, and human-computer interaction.

Whether you’re a seasoned designer or just starting out, understanding these laws will sharpen your instincts, strengthen your rationale during design reviews, and ultimately help you build products that people genuinely enjoy using.

1. Hick’s Law

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

Every additional option you present to a user adds cognitive load. This is why the best onboarding flows break complex processes into digestible steps, and why navigation menus that try to show everything at once tend to overwhelm rather than help.

In practice: Reduce the number of choices on screen. Use progressive disclosure to reveal options only when relevant. Prioritise the most common user actions and make them the easiest to find.

2. Fitts’s Law

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

Small buttons tucked into corners are hard to tap. Large, well-placed interactive elements are easy to reach. This law is especially critical in mobile design, where thumbs — not precision cursors — are doing the work.

In practice: Make primary action buttons large and place them within natural reach zones. Increase tap targets to at least 44×44 pixels (Apple’s recommendation) or 48×48dp (Google’s). Keep destructive actions away from frequently used buttons.

3. Jakob’s Law

Users spend most of their time on other sites, so they prefer your site to work the same way as all the other sites they already know.

This isn’t a call to kill creativity — it’s a reminder that familiarity reduces friction. When you deviate from established conventions (like placing the logo top-left or using a hamburger menu on mobile), you force users to relearn interactions they’ve already mastered elsewhere.

In practice: Leverage familiar UI patterns and conventions. Innovate where it adds genuine value, not where it creates confusion. Test unconventional designs rigorously before shipping.

4. Miller’s Law

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

This classic cognitive psychology finding has huge implications for interface design. Long lists of unorganised content, sprawling forms, and dense information architectures all strain the user’s ability to process and retain information.

In practice: Chunk information into groups of 5–9 items. Use clear headings and visual hierarchy to help users scan. Break long forms into logical sections or multi-step flows.

5. The Law of Proximity (Gestalt)

Objects that are near each other tend to be perceived as a group.

Spacing is one of the most powerful tools in a designer’s arsenal. The way you group — or separate — elements communicates relationships without a single word of explanation.

In practice: Group related elements closely together and use whitespace to create separation between distinct sections. Ensure form labels sit closer to their corresponding inputs than to adjacent fields.

6. The Law of Similarity (Gestalt)

Elements that share visual characteristics (colour, shape, size) are perceived as related.

Consistency in visual treatment helps users build mental models of your interface. When buttons that do similar things look different, or when unrelated elements look the same, you introduce confusion.

In practice: Use consistent styling for elements that share the same function. Differentiate primary, secondary, and tertiary actions through colour, weight, or size. Maintain a cohesive design system.

7. The Von Restorff Effect (Isolation Effect)

When multiple similar objects are present, the one that differs from the rest is most likely to be remembered.

This is the principle behind every highlighted “recommended” pricing tier, every contrasting call-to-action button, and every badge on a notification icon. Strategic contrast draws attention where it matters most.

In practice: Make your primary CTA visually distinct from surrounding elements. Use contrast sparingly — if everything stands out, nothing does. Highlight key information, errors, or status changes with colour and visual weight.

8. The Aesthetic-Usability Effect

Users often perceive aesthetically pleasing designs as more usable than less attractive ones.

Beautiful interfaces earn goodwill. Users are more forgiving of minor usability issues when a product looks polished and well-crafted. This doesn’t mean style over substance — it means that visual quality is part of the user experience.

In practice: Invest in visual polish alongside functional design. Use consistent typography, balanced spacing, and a considered colour palette. A well-designed UI signals professionalism and builds trust.

9. Tesler’s Law (The Law of Conservation of Complexity)

Every application has an inherent amount of complexity that cannot be removed — only moved.

Someone has to deal with the complexity: either the user or the system. Great design shifts that burden away from the user. This is why smart defaults, auto-detection, and contextual assistance exist.

In practice: Simplify the user-facing experience even if it means more work on the engineering side. Use intelligent defaults to reduce decision-making. Automate wherever possible without sacrificing user control.

10. Doherty Threshold

Productivity soars when a system and its users interact at a pace that ensures neither has to wait on the other — typically under 400 milliseconds.

Perceived performance matters just as much as actual performance. A fast interface feels responsive, professional, and trustworthy. A slow one feels broken, regardless of how well-designed the visuals are.

In practice: Optimise load times and provide instant feedback for user actions. Use skeleton screens, progress indicators, and optimistic UI updates to maintain the illusion of speed. Lazy-load non-critical content.

Wrapping Up

These laws aren’t rigid rules — they’re mental models grounded in how humans perceive, process, and interact with the world. The best designers don’t follow them blindly; they understand the reasoning behind each one and know when to lean into a principle and when to thoughtfully bend it.

Keep these laws in your toolkit. Reference them when making design decisions, use them to defend your choices in stakeholder conversations, and revisit them whenever an interface just doesn’t feel right. More often than not, the answer is hiding in one of these fundamentals.