Scroll Depth
Scroll depth tracking tells you how far down a page your visitors scroll. It answers a question that pageview counts cannot: do visitors actually see the content you have placed on a page, or do they leave before reaching it?
How scroll depth is measured
As a visitor scrolls down a page, the Statalog tracker records when they cross percentage-of-page-height thresholds. The thresholds are:
- 0% — the visitor loaded the page (all sessions start here)
- 25% — the visitor scrolled past the first quarter of the page
- 50% — the visitor reached the midpoint of the page
- 75% — the visitor scrolled past three-quarters of the page
- 100% — the visitor reached the bottom of the page
These thresholds are recorded as the highest point reached during a session on that page. A visitor who scrolls to 75% and then scrolls back up is recorded at 75%, not re-recorded at lower thresholds as they scroll back.
Like click heatmaps, scroll data is stored as aggregate counts per threshold bucket — not as individual visitor scroll records. The database stores the number of sessions that reached each threshold for each page, not a log of individual sessions.
Reading scroll depth data
Scroll depth is presented either as a percentage chart or as a gradient overlay on the page:
Percentage chart: Each threshold shows what percentage of page visitors reached that depth. For example:
- 0% reached: 100% (all visitors)
- 25% reached: 78%
- 50% reached: 54%
- 75% reached: 31%
- 100% reached: 12%
Gradient overlay: The page is shaded to indicate the drop-off point — the further down the page, the fewer visitors have seen that section. Sections seen by very few visitors appear visually de-emphasised.
What scroll depth tells you
The fold problem If 80% of visitors never scroll past 25% of the page, almost everything below the initial viewport is invisible to most of your audience. Any content, CTAs, or evidence you have placed lower on the page is not being seen. The solution is usually to move the most critical information higher — above the typical fold — or to redesign the page to create a stronger visual invitation to scroll.
Content length calibration If virtually no visitors reach the bottom of a very long page, the page may be too long for the audience's intent. Conversely, if a high percentage of visitors reach 100% on a short page, you may have an opportunity to add more value — related content, a stronger CTA, supporting evidence — that visitors are clearly open to consuming.
CTA placement validation If your primary CTA is placed at the 60% mark of the page and only 40% of visitors reach that depth, a maximum of 40% of visitors could ever see your CTA. Moving it higher — or adding a secondary CTA above the fold — would immediately expose it to more visitors.
Complementing click heatmaps
Scroll depth and click heatmaps answer different questions and are strongest when used together:
- Scroll depth tells you what percentage of visitors saw a given section of the page
- Click heatmaps tell you what visitors interacted with on the sections they did see
A section with high scroll reach but low click engagement suggests visitors see the content but are not moved to act on it. A section with relatively low scroll reach that nevertheless shows a hot click spot suggests the visitors who do reach it are highly engaged — worth considering whether you can draw more visitors down that far.
Same privacy approach
Scroll depth data is collected and stored with the same privacy architecture as click heatmaps. No individual scroll sessions are recorded. The stored data consists entirely of aggregate counts: how many sessions reached each threshold on each page. There is no way to reconstruct an individual visitor's scroll behaviour from the stored data.
No cookies are used. No consent banner is required.
Comparison with GA4
Google Analytics 4 includes a built-in scroll event, but by default it fires only once per session at the 90% threshold. This means GA4 tells you whether visitors nearly completed a page — but nothing about where the majority of drop-off occurs between 0% and 90%.
To get multi-threshold scroll data in GA4 you need to implement custom events for each threshold, which requires additional tag manager configuration or custom code. Statalog tracks all five thresholds automatically with no configuration required.
FAQ
Does scroll depth account for page length changes? Thresholds are calculated as a percentage of the total page height at the time the scroll event fires. If a page's height changes dynamically (e.g. content loads in below the fold), the percentage is based on the current document height at the moment of measurement. For pages with highly dynamic content, scroll percentages should be interpreted with this in mind.
What if a visitor opens the page but does not scroll at all? They are recorded at the 0% threshold. This is included in the data — it represents visitors who loaded the page but left without scrolling, which is a form of bounce behaviour and is captured in the Bounce Rate metric on the Pages report as well.
Is scroll depth available for all pages or only enabled ones? Scroll depth is part of the heatmaps feature and is enabled on a per-page basis, the same as click heatmaps. See Click heatmaps for instructions on enabling heatmap tracking for a specific page.