Scroll Depth

Scroll depth measures how far down a page a user scrolls—usually shown as a percentage (e.g., 25%, 50%, 75%, 100%). It’s a proxy for content consumption and engagement beyond a simple pageview. In Google Analytics 4 (GA4), the built-in Enhanced Measurement “scroll” event fires the first time a user reaches ~90% of a page; for other thresholds (25/50/75/100), you typically implement custom tracking via Google Tag Manager (GTM). 

Why It Matters

  • See if people read your content: Depth shows whether visitors reached important sections (e.g., pricing, FAQ).

  • Place CTAs and key info wisely: Most attention is near the top, NN/g found users spend ~57% of viewing time above the fold and ~74% in the first two screenfuls. 

  • Diagnose friction: Sudden drop-offs can signal layout, load-time, or relevance issues (pair with session replay/heatmaps). 

Examples

  • Blog post: Only 35% of visitors hit 50% depth → move the email signup higher and tighten intro.

  • Product page: 60% reach “Benefits” at 50% depth but only 15% reach “Pricing” at 80% → add a sticky CTA and shorten sections.

  • Landing page test: Variant B gets more users to 75% depth and shows higher form starts → keep B.

Best Practices

  1. Track meaningful thresholds. Use GTM’s Scroll Depth trigger to capture 25/50/75/100% events and send them to GA4. 

  2. Don’t rely on 90% only. GA4’s auto “scroll” event is handy, but it only fires at ~90%, add custom events for a fuller picture. 

  3. Combine depth with outcomes. Correlate scroll with micro-conversions (e.g., form start) and macro conversions (orders/leads) to avoid vanity metrics.

  4. Use heatmaps & replays. Scroll heatmaps (Hotjar/Crazy Egg) visualize where readers stop; investigate sharp fades with replays. 

  5. Design for attention. Since attention drops after the first screens, front-load value: clear headline, benefits, and a visible CTA. 

  6. Mind special layouts. Infinite scroll, dynamic content, or very short pages can distort depth, validate with behavior metrics and replays.

Related Terms

  • Engaged Sessions / Engagement Time (GA4)

  • Heatmaps (Scroll/Click) 

  • Above the Fold 

  • Micro-Conversions / Funnel Analysis

FAQs

Q1. How do I set up scroll depth in GA4?
Turn on Enhanced Measurement for the built-in scroll (90%) event, then add GTM Scroll Depth triggers for 25/50/75/100% and send custom events to GA4. 

Q2. What’s a “good” scroll depth?
Depends on page length and purpose. For long articles, aim for a strong 50% reach rate to mid-content and optimize for 75%; for landing pages, push key value/CTAs above 50% because attention falls with depth. (NN/g time-on-fold research supports front-loading value.) 

Q3. Does high scroll depth mean high engagement?
Not always. Someone can scroll fast without reading. Pair depth with time on page, clicks, form starts, or conversions.

Q4. Can I see where people stop visually?
Yes, use scroll heatmaps (Hotjar/Crazy Egg) to see the drop-off gradient and reposition content/CTAs accordingly. 

Q5. Any GTM pitfalls?
If a page loads near the bottom, GTM may fire multiple thresholds at once (e.g., reload at bottom triggers 25/50/75/100). Account for this in logic. 

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