10 Essential UX Laws Every Designer Should Know

If you’re designing interfaces without knowing these laws, you’re just guessing. Plain and simple. You might get lucky sometimes, but more often than not, you’re building products that frustrate users and kill conversions.

These aren’t fluffy design principles someone pulled out of a MBA textbook. These are hard-won findings from decades of research in human-computer interaction. They’re the rules that separate products people tolerate from products people actually want to use.

Let’s get into it.

:::note[TL;DR]

Fitts’s Law: Big, close targets are fast to click. Stop making tiny buttons.
Jakob’s Law: Users don’t learn your app—they bring expectations from every other app. Don’t fight that.
Hick’s Law: More options = slower decisions = users bouncing. Simplify your menus.
Miller’s Law: Humans juggle about 7 things in memory. Anything more needs grouping.
Parkinson’s Law: Deadlines make stuff get done. Use urgency in your flows.
Tesler’s Law: You can’t remove all complexity. Decide what the user must handle.
Law of Proximity: Things close together = related. Group intelligently.
Postel’s Law: Accept weird input, but output clean data. Be forgiving.
Serial Position Effect: First and last items remembered best. Put key actions at edges.
Occam’s Razor: Straight solution beats clever solution. Always. :::

The 10 Laws That Actually Matter

1. Fitts’s Law — Hit What You Aim At

Time to acquire a target = f(distance, size)

The further away something is, the longer it takes to get there. The smaller it is, the harder it is to hit. That’s Fitts’s Law in plain English.

Fitts's Law visualization showing target size and distance relationship Source: struto.co.uk

This is why Mac OS puts the Dock at the bottom of the screen—it’s always reachable and easy to hit. Amazon’s “Buy Now” button? Giant. Bright. Dead center on mobile. Not an accident.

Your takeaway: Make primary actions big and place them where thumbs already are. Don’t bury the call-to-action in a corner.

2. Jakob’s Law — Don’t Reinvent the Wheel

Users spend most of their time on other sites. They expect your site to work the same way.

People don’t learn your app. They bring their muscle memory from every other app they’ve ever used. Fight that, and you lose.

Jakob's Law - users prefer familiar patterns Source: struto.co.uk

Search goes in the top right. The hamburger menu hides navigation. The logo links home. These aren’t creative constraints to break—they’re user expectations to leverage.

Instagram, Twitter, Airbnb—all use nav bars people already understand. Same patterns. Less friction. More usage.

Your takeaway: Use established design patterns unless you have a damn good reason not to.

3. Hick’s Law — Choice Paralysis is Real

Decision time increases with the number of options.

Walk into a restaurant with a 47-item menu. You freeze. You scan. You get annoyed. You probably just order whatever your friend is having.

Now walk into a place with 3 options. You point, you eat, you move on.

Hick's Law - decision time increases with options Source: struto.co.uk

Netflix doesn’t show you everything. They show you rows of curated content because dumping 10,000 titles on you would mean you choosing none of them. Spotify Discover Weekly? Curated playlists, not random chaos.

Your takeaway: Limit choices per screen. Use filters, categories, and progressive disclosure.

4. Miller’s Law — Memory Has Limits

People can hold about 7 (plus or minus 2) items in working memory.

This is chunking. Phone numbers break into 3-3-4 digits. Credit cards break into 4-4-4-4. Not because it’s pretty—because it works.

Miller's Law - 7±2 items in working memory Source: onething.design

Gmail shows you emails grouped by date and labeled. Not a flat list of 14,000 emails. Tesla groups driving controls into categories—Vehicle, Climate, Media—not one giant menu.

Your takeaway: Chunk content. Group related items. Don’t dump 15 unrelated features on one screen.

5. Parkinson’s Law — Urgency Drives Action

A task expands to fill the time available for it.

Without a deadline, people procrastinate. With a ticking clock, they move.

Parkinson's Law - task expands to fill available time Source: pinimg.com

That’s why Amazon shows “Only 2 left in stock.” That’s why flash sales work. That’s why Netflix says “Coming in 3 days.”

One-time passwords in banking expire in 30 seconds for a reason. The clock forces action.

Your takeaway: Add scarcity and time constraints to critical flows. But don’t fake it—users see through that.

6. Tesler’s Law — Complexity Has a Floor

There’s a baseline amount of complexity that can’t be reduced.

You can optimize, hide, and simplify—but you can’t eliminate the essential complexity every task requires.

Tesler's Law - complexity cannot be completely reduced Source: lawsofux.com

Filing your taxes, for instance, has legal fields the government demands. You can’t magic those away. The Uber app still needs you to confirm pickup and drop-off locations. That’s core functionality.

Tesla’s autocomplete on addresses is their answer—you handle less typing, but the system handles the complexity.

Your takeaway: Find the complexity the user must handle and make it as painless as possible. Everything else is your job to absorb.

7. Law of Proximity — Close Things Belong Together

Elements near each other are perceived as related.

This is Gestalt psychology in action. Your brain groups near things automatically—it can’t help it.

Law of Proximity - related elements grouped together Source: uxmisfit.com

Google Search results? Title, URL, and description are stacked tight. The next result is clearly separate. No borders needed—it just reads right.

Inbox by Gmail groups an email with its preview text, sender, and time—all touching. Then a visible gap. Then the next email.

Your takeaway: Use whitespace to separate unrelated content. Use proximity to group related content. Don’t rely on lines and borders to do your thinking for you.

8. Postel’s Law — Be Flexible In, Conservative Out

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

People type weird stuff. Different phone formats. Caps-lock names. Extra spaces. They don’t follow your rules.

Postel's Law - be liberal in input, conservative in output Source: lawsofux.com

Airbnb accepts “+1-555-123-4567” and normalizes it to something clean internally. Stripe accepts cards in any format but outputs clean JSON.

YouTube handles typos in search—did you mean “Rick Astley”? Yes, they knew what you meant.

Your takeaway: Accept varied input, parse it intelligently, and output clean, standardized data. Never make users jump through hoops your system should handle.

9. Serial Position Effect — Edges Stick

First and last items in a sequence are remembered better than middle items.

The primacy effect: You remember the start. The recency effect: You remember the end. The middle? Forgotten.

Serial Position Effect - first and last items remembered Source: springernature.com

App onboarding screens: key info goes on the first slide or the last. Never bury your main value prop in slide 3.

Amazon’s “Add to Cart” is right there. First. The “Continue to Cart” button is at the end. They know you’re closing a loop.

Your takeaway: Put the most important action at the beginning or end. Never in the middle of a flow.

10. Occam’s Razor — Simple Wins

The simplest solution is usually the right one.

Complex solutions break. Simple solutions scale. Users don’t want options—they want to get stuff done.

Google’s homepage is literally a box and two buttons. That’s not minimalism for aesthetics—that’s the most effective design for the core task.

Apple removes the headphone jack, the home button, the SIM tray tool. They’re not sadists—they’re betting that simpler interfaces beat feature-rich ones that nobody figures out.

Your takeaway: If you can’t explain the feature in one sentence, reconsider it. Complexity is easy to add. Hard to remove. Be ruthless.

FAQ

Do these laws ever conflict with each other?

Yep. Fitts’s Law wants big targets. Occam’s Law wants minimal UI. Sometimes you can’t have both big buttons and no buttons. The fix: prioritize what actually matters for your user’s main task and compromise on the rest.

Should I memorize all these exactly?

No. Understand the why behind each one. When you know the principle, you can spot problems in your designs without pulling up a cheat sheet.

These seem too basic. Is there anything more advanced?

These are basics—but basics are where most designers fail. Advanced comes after you’ve nailed the fundamentals. 80% of bad UX is breaking one of these rules.

Do these apply to mobile and desktop the same?

Mostly yes. Fitts’s Law gets even stricter on mobile—touch targets need to be 44px minimum. Hick’s Law hits harder when screen real estate is tiny. The principles scale; your implementation just gets tighter.

What’s the fastest law to fix in my current product?

Start with Hick’s Law. Audit how many options you’re showing per screen. I bet you can cut half of them and improve your conversion.

Summary

Fitts’s Law is why button size and placement matter—in practice at Amazon and Mac OS.
Jakob’s Law is why fighting user expectations loses—use familiar patterns.
Hick’s Law is why choice overload kills decisions—Netflix curates instead of dumping.
Miller’s Law is why chunking works—groups of 7±2 for memory.
Parkinson’s Law is why scarcity accelerates action—real deadlines drive real behavior.
Tesler’s Law is why you can’t simplify everything—essential complexity exists.
Law of Proximity is why spacing matters—near equals related.
Postel’s Law is why input parsing matters—accept weird, output clean.
Serial Position Effect is why edges win—first and last beat the middle.
Occam’s Razor is why simple wins—complication is the enemy.

These aren’t suggestions. They’re the physics of how humans interact with technology. Ignore them at your own risk.