Scroll depth: definition and measuring engagement
Updated on February 22, 2026
Quick definition
Scroll depth is the percentage of a web page that users scroll down before navigating elsewhere or leaving the site. It is a behavioural indicator that reveals whether visitors are actually reading your content or skimming it before leaving — a complement to bounce rate and average time on page.
How it works
Scroll depth is measured by recording analytics events at predefined scroll thresholds: typically at 25%, 50%, 75% and 100% of the total page height. For each session, the highest threshold reached is recorded.
Example: if 1,000 users visit a blog post and 400 reach 75% of the page, scroll depth at 75% is 40%.
This metric is especially valuable for long-content pages (articles, landing pages, detailed product pages) where the position of key elements (CTAs, forms, testimonials) directly influences conversions.
Analysing scroll depth often reveals surprising insights: if 70% of users don't go past 30% of a long page, elements positioned lower are practically invisible to most of the audience.
Combined with heatmaps and session recordings, it enables optimisation decisions based on real user behaviour.
Why it matters
Scroll depth is a far more reliable engagement indicator than simple bounce rate or time on page, because it measures a physical, intentional action by the user.
For copywriters and content managers, knowing that 60% of readers drop off after the first two paragraphs is decisive information:
- Rethink content structure (place key information at the top)
- Improve hooks and subheadings to encourage continued reading
- Position CTAs at the level where most users still scroll
How to improve or use it
- 1Structure your articles with strong hooks and engaging subheadings that encourage continuation.
- 2Place your most important elements (CTAs, offers, social proof) in the zone where most users still scroll (typically the top 50–75%).
- 3Shorten and lay out long content with breathing room: dense text blocks discourage reading.
- 4Use visual elements (images, videos, infographics) to maintain attention.
- 5Test different page lengths and structures with A/B tests, using scroll depth as the primary metric.
With Sublim
Sublim natively records scroll-depth events (25%, 50%, 75%, 90%) for all pages on your site, with no extra configuration. This data is available by URL and segmentable by traffic source, device and time period — fine-grained insight into user engagement, without tracking cookies, GDPR-compliant.
Frequently asked questions
How do you measure scroll depth in Google Analytics 4?
GA4 natively includes a scroll event that fires when the user reaches 90% of the page. To measure finer thresholds (25%, 50%, 75%), you need to configure custom events via Google Tag Manager using scroll-depth triggers with percentage thresholds.
What is the difference between scroll depth and a scroll heatmap?
Scroll depth is a quantitative metric (what percentage of the page each user reached). The scroll heatmap is an aggregated visual representation that shows, through a colour gradient, which areas of the page are most viewed. The two are complementary: depth provides exact figures, heatmaps offer instant visual reading.
Does low scroll depth always mean the content is bad?
Not necessarily. For quick-answer pages (FAQs, short definitions, contact pages), the user may get the information they were looking for at the start of the page and leave satisfied. You should always analyse scroll depth in relation to the page's goal and conversion rate.
Related terms
Average time on page is the average duration that visitors spend on a …
The bounce rate is the percentage of [sessions](session) in which a us…
A heatmap (or [heat map](carte-de-chaleur)) is a visual representation…
An analytics event is a specific user interaction with your site or ap…