Scroll depth tracking gives you a simple way to understand how people engage with your content. Benjamin Mangold provides an excellent tutorial on how you can add scroll depth tracking to your google analytics. Watch below:
Enable the built-in scroll variables inside Google Tag Manager
Next, create a new tag by navigating to ‘Tags’ and clicking ‘New’.
Click on the trigger panel (below the tag) and click on the plus sign to create a new trigger.
Save the trigger and the tag, then publish the changes to your website.