How do I measure scroll depth with percentages (like 25%, 50%, 75%) in GA4 using GTM?

by · Published · Updated

Applies to: Google Analytics 4 (GA4), Google Tag Manager (GTM)
Last updated: May 2025

Problem

GA4’s built-in Enhanced Measurement only tracks when a user scrolls to 90% of a page. You want more granular scroll depth tracking—such as at 25%, 50%, and 75%—to better understand content engagement.

Solution

You can configure Google Tag Manager to track scroll percentages and send custom events to GA4 with scroll data (e.g., how far down the page users scroll).

Step-by-Step Guide

Step 1: Enable Scroll Depth Trigger in GTM

  1. Go to https://tagmanager.google.com
  2. Open your container
  3. Go to Triggers > New
  4. Choose Trigger Type: Scroll Depth
  5. Configure the trigger:
    • Vertical Scroll Depths: enter 25,50,75
    • Check Percentages
    • Fire trigger on All Pages (or restrict as needed)
  6. Name it (e.g., “Scroll Depth Trigger”) and save

Step 2: Enable Scroll Variables

  1. Go to Variables > Configure
  2. Enable:
    • Scroll Depth Threshold
    • Scroll Depth Units
    • Page Path

Step 3: Create a GA4 Event Tag

  1. Go to Tags > New
  2. Choose Tag Type: GA4 Event
  3. Configure the tag:
    • Event Name: scroll_depth
    • Event Parameters:
      • scroll_percent: {{Scroll Depth Threshold}}
      • page_path: {{Page Path}}
  4. Attach the Scroll Depth Trigger created in Step 1
  5. Save and publish the tag

Step 4: Test the Setup

  1. Use Preview mode in GTM
  2. Navigate to a page on your site and scroll down
  3. In the preview panel, confirm that the tag fires at 25%, 50%, and 75%
  4. Check GA4 DebugView to confirm receipt of scroll_depth events

Step 5: Register Custom Parameters (Optional)

To analyze scroll percent in GA4 reports:

  1. Go to Admin > Custom Definitions > Create Custom Dimension
  2. Set:
    • Name: Scroll Percent
    • Scope: Event
    • Parameter name: scroll_percent
  3. Save

Viewing Scroll Depth Data

  • Use Reports > Engagement > Events to see scroll_depth
  • Use Explorations to segment by scroll percent, page, device, or traffic source
  • Combine with other metrics (e.g., time on page or conversion rate) to assess content effectiveness

Notes

  • This setup is more flexible than GA4’s native 90% scroll event
  • Consider filtering by page templates (e.g., only blog posts or landing pages) to avoid clutter
  • Avoid excessive tracking thresholds (e.g., every 10%) to limit event noise

Tags:

You may also like...