Track Blog reading like a Pro:Scroll Tracking + GTM in analytics

How many people are really reading the blog article? But what I really want to know is: how much time people spend reading my article, and how far they scroll through it — insights I can gather by using Google Tag Manager in Analytics.

Why I Want to Know, How Many Time Spend my Customer reading Blog article?

Not everyone who clicks on a blog post actually reads it.
Tracking scroll depth helps me see who just skimmed through and who really engaged with the content.
This information is key for me, because I put effort into writing articles.

And I want to know which topics and categories resonate most with my audience.

For example, when I decide to add a popup with a call-to-action or a newsletter form inside an article, I need to know the right moment to show it.
That means I have to understand which parts of the article readers actually reach and how much time they spend there.

Thanks to this data, I can also identify which types of articles are read the most.

And then target those topics and optimize my blog strategy accordingly.

Table of contents

• Why I Want to Know, How Many Time Spend my Customer reading Blog article?
• What do you need to implement scroll tracking in Google Tag Manager in analytics?
• Step 1: Create scroll tracking in GTM
  • Enable Scroll Variables in GTM
  • Create a Scroll Trigger
• Step 2: Create a GA4 tag for the scroll event
• Step 3: Testing your tag in Google Tag Manager Assistant
• Step 4: Analyzing data in GA4
  • Where to see scroll events in GA4?
  • How to do it
  • How to create a custom report (Explorations)
• Conclusion: leveraging Google Tag Manager in Analytics

What do you need to implement scroll tracking in Google Tag Manager in analytics?

Google Tag Manager account — obviously, with your website connected to GTM. How to connect your website with GTM can be read here.

Scroll Depth Trigger — GTM has a built-in Scroll Depth trigger you can enable. It tracks vertical scroll percentage or pixels.

Tag to send scroll data — usually a Google Analytics 4 (GA4) event tag configured to fire on the Scroll Depth trigger.

Variables (optional but helpful) — like Scroll Depth Threshold, Scroll Direction, or Scroll Percent, to capture details about the scroll event.

Testing tools — GTM Preview mode and GA4 DebugView help you test and verify the scroll tracking is working.

Step 1: Create scroll tracking in GTM

Scroll tracking allows you to monitor how far users scroll down on your website pages.

By enabling built-in scroll variables, creating a scroll trigger, and firing tags when users reach certain scroll depths (like 25%, 50%, 75%, or 100%), you can track scroll events effectively.

Enable Scroll Variables in GTM

1. Open your GTM account and go to Variables.
2. Click on Configure (top right).
3. Check all variables under Scroll Variables, for example:
   • Scroll Depth Threshold
   • Scroll Depth Units
   • Scroll Direction

Create a Scroll Trigger

Once I have the variables defined, I need to create a trigger.

You need to decide whether you want to track the entire website, just certain articles, or a specific section like a blog.

Since my website consists only of articles, I chose to track contains /, because I don´t have a blog category.

1. Go to Triggers.
2. Click New.
3. Choose the trigger type: Scroll Depth.
4. Set:
   • Scroll Depth Units: Percent (to track scroll by percentage).
   • Scroll Depth Thresholds: 25, 50, 75, 100 (this means the trigger will fire when the user scrolls to 25%, 50%, 75%, or 100% of the page).
   • Scroll Direction: Vertical.
   • If you want your trigger to fire on all pages, select the All Pages option.
   • If you want the trigger to fire only on blog articles, set a condition based on your URL, for example:
   • Choose Page URL
   • Select contains
   • Enter a part of your blog URL like /blog or /articles or /
   • This way, the trigger will only activate on pages that match that URL pattern.
5. Name the trigger, e.g. “Article | Scroll Depth | 25,50,75,100”, and save it.

Step 2: Create a GA4 tag for the scroll event

Thanks for creating the GA4 tag.

Now I can clearly check the data from scroll tracking. In GA4, I get valuable insights that I use to optimize my blog.

So, let’s continue.

1. Go to Tags.
2. Click New.
3. Select tag type, e.g., Google Analytics: GA4 Event
4. Fill in the event details:
5. Event name: scroll_depth_threshold
6. Event parameter: scrolled_percent
7. Value: {{Scroll Depth Threshold}}
8. In the Trigger section, select your scroll trigger created earlier: Scroll Depth
9. Name the tag and Save it.

Step 3: Testing your tag in Google Tag Manager Assistant

When I created my scrolling tag, I needed to check if everything was working correctly.

So, I clicked on Preview to open Tag Assistant.

I chose an article and started scrolling down.

If everything works as expected, my tags should fire.

Then, I go to GA4, click Admin and open DebugView to see the events in real time. If everything looks good, I go back and submit my tag.

Step 4: Analyzing data in GA4

Where to see scroll events in GA4?

GA4 has a built-in scroll event, but if you’re sending custom events, find them here:

GA4 → Reports → View User Engagement → Events

You’ll see a list of events – look for your custom ones like scroll_depth_treshold etc.

If you’re sending custom parameters like scroll_percent: 50, you must register them in GA4 as custom dimensions to see them in reports.

How to do it:

1. In GA4, go to Admin → Custom definitions
2. Click Create custom dimension
3. Name it Scrolled_percent_25_50_75_100
4. Scope: Event
5. The parameter name must match exactly what you use in your tag – e.g., scrolled_percent
6. Save

Once created, the parameter will appear in your Explorations.

How to create a custom report (Explorations)

To dig deeper into scroll data, create an Exploration.

So, let´s continue.

Steps:

1. Go to Explore in the GA4 menu.
2. Click on Blank to start a new exploration.
3. Name your report (e.g., “Article Scroll Tracking”).
4. Add Dimensions like:
   • Event name
   • Page path or Page title
   • Any custom parameter you send (e.g., scroll_percent)
5. Add Metrics like:
   • Event count
6. In the „Rows“ section, add Page title; in „Columns“, use Event name or scrolled_percent; and in „Values“, use event count.

Conclusion: leveraging Google Tag Manager in Analytics

I have to say that using scroll tracking in Analytics is perfect for me. It allows me to identify exactly which articles are interesting to my audience.

Based on the data, I can add a call to action within the article, or see which articles are scrolled to 100% and which are not.

This helps me understand which content performs best and inspires me to write more on those topics.

I recommend adding and using scroll tracking tags on your website. In a future article, I’ll write about timer tags.

Thanks for reading!

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