scrolldepth

Scrolldepth is a web analytics metric that records how far a visitor scrolls down a page, typically expressed as a distance from the top in pixels or as a percentage of the page’s total height. It serves as an indicator of reader engagement with page content, complementing metrics like time on page and page views.

Measurement is usually accomplished with client-side scripting that tracks the window scroll position and the document height. The maximum scroll depth reached during a session can be recorded, and data are often aggregated by page. Analysts commonly report scroll depth at common thresholds such as 25%, 50%, 75%, and 100%, or as the average depth across sessions.

Uses of scrolldepth include evaluating content effectiveness, informing layout and length decisions, and guiding content placement and call-to-action positioning. It is also employed in A/B testing to determine whether longer or shorter pages improve engagement or conversions. By comparing scroll depth across pages, marketers can identify which content holds attention and where to optimize structure or headlines.

Implementation considerations include the availability of scroll-tracking features in analytics platforms, or the use of dedicated libraries such as scrolldepth.js to standardize event reporting. Limitations and caveats involve dynamic content loading, sticky headers, or lazy loading that can affect depth measurements; privacy and consent requirements; and potential inaccuracies due to sampling, ad blockers, or cross-domain pages.