Scroll depth tracking is not new but now you can set it up in a jiffy.
Log into Google Tag Manager (GTM) and then click on “Triggers” in the left navigation.
Select new and then click on the pencil icon in the top right of the box.
Select “Scroll Depth” in the right hand column.
Depending on what you want you can either select vertical or horizontal scroll depth tracking.
Add the percentages for when the trigger will fire. In this case 10%, 25%, 50%, 75% and finally 100%, which is at the bottom of the page.
If you only want this trigger to fire on certain pages you can specify “some pages” and then add the path, as shown below.
Save the trigger and press preview (top right) to test the trigger is firing correctly.
In the same browser that you have GTM open open the site. You will see GTM’s debugger frame open at the bottom.
As you scroll you will see the data object being pushed. So success.
Set up Google Analytics Event Tag
In GTM click on Tag (left column) then new. Click on the pencil to then select Universal Google Analytics as shown below.
Configure the new tag as follows