Jakob's Law
The principle that users spend most of their time on other websites and therefore prefer your site to work the same way as those they already know, favoring familiar interaction patterns.
What Is Jakob's Law?
Jakob's Law, coined by usability expert Jakob Nielsen, states that users develop expectations from cumulative experience with other websites. Their mental models — cart in top right, search bar at top, logo links to home — are built on thousands of hours spent on sites that are not yours. When your interface violates these patterns, users do not marvel at your originality; they experience friction because their existing schema no longer applies. Convention is not a creative failure; it is conversion infrastructure.
Also Known As
- UX and design: "convention over invention," "pattern familiarity"
- Product and engineering: "standard UX patterns," "platform conventions"
- Marketing and growth: "familiar user flow," "expected interactions"
- Engineering: "design system adherence"
How It Works
A redesigned checkout moves the "Place Order" button to the top-left of the final step because a designer argued it creates a stronger visual moment. Users who have completed thousands of checkouts look bottom-right (where every major retailer places it), fail to find the button, scroll, get confused, and a percentage abandon. The interface is objectively prettier; the mental model violation silently taxes every session.
Best Practices
- Put cart in top right, logo top-left-linking-home, search at top, and primary CTAs bottom-right of their container.
- Use icon conventions without reinventing them: magnifying glass for search, gear for settings, bell for notifications.
- Innovate on content, narrative, and brand — leave interaction patterns conventional unless you have strong evidence a novel pattern wins.
- When you must deviate, compensate with extra signifiers (labels, tooltips, visual weight) to bridge the mental model gap.
Common Mistakes
- Novelty-for-novelty's-sake navigation (horizontal-only, hidden-unless-hover, custom icons without labels) that wins design awards and loses conversions.
- Assuming your power users "will figure it out" — they will, but your first-time visitors will not, and first-time visitors are where conversion lives.
Industry Context
SaaS and B2B: admin dashboards benefit from mirroring tools like Gmail or Notion that users know; novel IA costs onboarding time. Ecommerce and DTC: violating checkout conventions almost always hurts — Amazon's patterns are the global baseline. Lead generation: form layouts, field orders (name → email → phone), and submit button placement all follow Jakob's Law expectations.
The Behavioral Science Connection
Jakob's Law is downstream of cognitive fluency: familiar patterns process faster, feel more trustworthy, and require less conscious attention. Violating them forces System 2 deliberation where System 1 autopilot would have converted.
Key Takeaway
Innovate on content and brand; follow conventions on interaction — novelty in navigation is a conversion tax disguised as creativity.