Scroll in UX: Types, Metrics & Best Practices

Scrolling is one of the most natural and frequent interactions on the web. We do it dozens of times a day without thinking: swiping on a phone or spinning the mouse wheel to see more content. But behind this everyday action lie design decisions that directly impact user experience and conversion.

In this article we will explain what scroll means in UX, what types exist, how to measure scroll depth as a CRO metric, and what the best practices are to make sure users reach exactly where you need them to.

What is scroll

In the web context, scroll (or scrolling) is the action of moving a page's visible content up, down, left, or right to access content that does not fit on the screen. The term comes from the English to scroll, meaning to move or roll through.

Scrolling exists because web pages contain more information than a single screen can display at once. In the early days of the web, there was a myth that "everything important must be above the fold." Today, in the mobile era, scrolling is the primary way people consume content.

Types of scroll in web design

Not all scrolling is the same. Each type has its advantages, its risks, and its optimal use cases.

Traditional scroll (finite)

The standard scroll: the page has a defined beginning and end. The user scrolls down and, upon reaching the footer, there is no more content. It is the most predictable and the most widely used.

When to use it: on most web pages — articles, landing pages, product pages.

Infinite scroll

Content loads automatically as the user scrolls, with no need to click "next." There is no visible end.

Examples: social media feeds (Instagram, X), Pinterest, some e-commerce sites.

Advantages:

• Keeps users engaged.
• Eliminates the friction of pagination.

Disadvantages:

• Makes it hard to reach the footer (if one exists).
• Can cause fatigue and a sense of lost control.
• Worse for SEO: pages without defined pagination are harder to crawl.

Parallax scroll

Different design layers move at different speeds during scrolling, creating a three-dimensional depth effect. It is visually striking but can be problematic.

Advantages:

• Creates immersive, memorable experiences.
• Ideal for visual storytelling.

Disadvantages:

• Can cause dizziness or discomfort in sensitive users.
• Slows down the page if not well optimized.
• Can distract from the main content.

Sticky scroll (fixed elements)

Certain page elements — such as the navigation, a CTA, or a summary — remain fixed on screen while the user scrolls through the rest of the content.

Examples: sticky navigation menus, fixed "Add to cart" buttons on mobile, progress bars.

Advantages:

• Keeps key elements accessible.
• Reduces conversion friction.

Scroll type	Experience	Main risk	Best use
Traditional	Predictable	None significant	All types of sites
Infinite	Addictive	Fatigue, poor SEO	Feeds, large catalogs
Parallax	Immersive	Performance, dizziness	Storytelling, portfolios
Sticky	Functional	Taking up useful space	CTAs, navigation

Scroll depth: the CRO metric you should be measuring

Scroll depth measures how far down a page users actually get. It is typically expressed as a percentage: a scroll depth of 75 % means the user has seen three-quarters of the page.

Why it matters

• It reveals whether content engages: if most users drop off at 25 %, something is wrong with the top of the page.
• It shows where to place CTAs: if 80 % of users reach 50 % of the page, your main CTA should be there or earlier.
• It complements bounce rate: a user can bounce (visit a single page) yet still have read the entire article. Scroll depth adds context.

How to measure scroll depth with GA4

Google Analytics 4 automatically records a scroll event when the user reaches 90 % of the page. But for more granular analysis, you need to set up custom events:

1. In Google Tag Manager, create a Scroll Depth trigger.
2. Set the thresholds: 25 %, 50 %, 75 %, 90 %.
3. Create a GA4 tag that sends a custom event (e.g., scroll_depth) with the percentage as a parameter.
4. In GA4, register scroll_depth_percentage as a custom dimension so you can segment and analyze.

With this setup, you can see in GA4 what percentage of users reaches each threshold on every page, giving you the data to optimize structure and CTAs.

Scroll best practices in UX

1. Signal that there is more content

If the visible portion of the page looks complete, users will not scroll. Use visual cues like arrows, truncated text, partially visible images, or subtle animations that invite scrolling.

2. Fast loading

Scrolling loses all effectiveness if the page is slow to load. Optimize images, use lazy loading, and minimize unnecessary JavaScript. Smooth scrolling requires a fast page.

3. Progressive content

Structure your content so that every section of the scroll adds value. Do not pad with low-quality content just to make the page longer. A short page that hooks is better than a long page that bores.

4. CTAs visible without scrolling (and reinforced during scrolling)

Your main CTA should be visible without scrolling (above the fold), but it should also repeat at strategic points throughout the page. A sticky CTA on mobile is an excellent practice for long pages.

5. Avoid horizontal scroll

Horizontal scrolling feels unnatural on the web and frustrates users. It is only acceptable in very specific cases like image carousels or wide data tables on mobile. Even then, clearly signal that there is hidden content to the right.

6. Progress bar

On long articles, a progress bar at the top tells users how much is left to read. It reduces uncertainty and motivates them to finish.

7. Respect native scroll

Avoid hijacking the scroll (scroll hijacking) — that is, modifying the speed or natural behavior of scrolling. It is one of the most hated practices among users and can cause immediate frustration.

Scroll and conversion

Scrolling is not just a navigation interaction. It is an indicator of interest and engagement:

• Users who scroll deeply are more engaged and more likely to convert.
• The position of conversion elements relative to scroll depth is critical. A form that only 20 % of users ever see needs to be repositioned.
• In A/B tests, moving content sections and measuring the impact on scroll depth is a highly effective CRO technique.

Conclusion

Scrolling is how users consume your content. Measuring how they do it — with scroll depth — and designing to facilitate it — with UX best practices — are two pillars of conversion optimization.

Do not assume all your users read the entire page. Measure, analyze, and adjust. Scroll data will tell you exactly where you lose your audience and where to place your conversion elements.

If you want to optimize your website's experience for higher conversions, check out our CRO agency services or start with a free analysis on Scan&Boost.

— Adrià Vidal