Universal Analytics to GA4 Migration: What You Need to Know

Universal Analytics (UA) was officially deprecated by Google on July 1, 2023. If you haven’t yet migrated to Google Analytics 4 (GA4), you’re losing traffic data for your website. This guide explains the key differences and helps with migration.

Universal Analytics Status

Date	Event
July 2023	UA stopped collecting new data
July 2024	Access to historical UA data ended

If you don’t have GA4 yet, you need to implement it immediately - every day without GA4 is lost data.

Key Differences: UA vs GA4

Data Model

Aspect	Universal Analytics	GA4
Basic unit	Session	Event
Page views	pageview hit	page_view event
Users	Cookie-based	User ID + Device ID
Bounce rate	Sessions without interaction	Replaced by Engagement rate
Conversion paths	Linear	Data-driven attribution

Event Model

Universal Analytics:

// UA - category, action, label
ga('send', 'event', 'Video', 'Play', 'Homepage Video');

GA4:

// GA4 - event name + parameters
gtag('event', 'video_play', {
  video_title: 'Homepage Video',
  video_duration: 120
});

Standard GA4 Events

GA4 defines recommended events:

Event	Usage
`page_view`	Page view
`scroll`	Scroll 90% of page
`click`	Outbound link click
`view_search_results`	Search results
`file_download`	File download
`purchase`	Purchase (e-commerce)
`sign_up`	Registration
`login`	Login

How to Implement GA4

Option 1: gtag.js (directly)

<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-XXXXXXXXXX"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());
  gtag('config', 'G-XXXXXXXXXX');
</script>

Option 2: Google Tag Manager (recommended)

Create a GA4 Configuration tag in GTM
Enter Measurement ID (G-XXXXXXXXXX)
Trigger: All Pages
Publish container

Details about GTM: dataLayer Best Practices

Option 3: Server-Side GTM

For better performance and privacy: GTM Server-Side vs Client-Side

E-commerce Migration

UA Enhanced Ecommerce → GA4 Ecommerce

Event names have changed:

UA Event	GA4 Event
`productClick`	`select_item`
`addToCart`	`add_to_cart`
`removeFromCart`	`remove_from_cart`
`checkout`	`begin_checkout`
`purchase`	`purchase`

Data Structure

UA Enhanced Ecommerce:

dataLayer.push({
  'event': 'addToCart',
  'ecommerce': {
    'add': {
      'products': [{
        'name': 'Product',
        'id': 'SKU123',
        'price': '99.99',
        'quantity': 1
      }]
    }
  }
});

GA4 Ecommerce:

dataLayer.push({ ecommerce: null }); // Clear previous
dataLayer.push({
  'event': 'add_to_cart',
  'ecommerce': {
    'currency': 'USD',
    'value': 99.99,
    'items': [{
      'item_id': 'SKU123',
      'item_name': 'Product',
      'price': 99.99,
      'quantity': 1
    }]
  }
});

Goals Migration (Goals → Conversions)

In GA4, there are no “goals” - there are conversions, which are marked events.

How to Create a Conversion in GA4

Go to Admin → Events
Find the event you want to track as a conversion
Enable the Mark as conversion toggle

Or create a new event:

Admin → Events → Create event
Define conditions (e.g., page_location contains /thank-you)

What Happened to UA Metrics?

Bounce Rate → Engagement Rate

GA4 doesn’t have traditional Bounce Rate. Instead:

Engagement rate - % of engaged sessions (>10s, 2+ page views, or conversion)
Engaged sessions - number of engaged sessions

Average Time on Page → Average Engagement Time

GA4 measures actual time when the page is in the foreground.

Users

UA	GA4
Total Users	Total users
New Users	New users
-	Active users (default)

Exporting Historical UA Data

Google ended access to UA data in July 2024. If you have a copy:

BigQuery Export

If you exported UA data to BigQuery, you have it forever.

PDF/CSV Reports

Export key reports before losing access.

Google Analytics API

# Example export via API (Python)
from googleapiclient.discovery import build

analytics = build('analyticsreporting', 'v4', credentials=credentials)

response = analytics.reports().batchGet(
    body={
        'reportRequests': [{
            'viewId': 'VIEW_ID',
            'dateRanges': [{'startDate': '2020-01-01', 'endDate': '2023-06-30'}],
            'metrics': [{'expression': 'ga:sessions'}],
            'dimensions': [{'name': 'ga:date'}]
        }]
    }
).execute()

GA4 Integration with Other Services

Google Ads

Admin → Product Links → Google Ads Links
Connect accounts
Enable automatic conversion import

Search Console

Admin → Product Links → Search Console Links
Connect Search Console property

BigQuery

Admin → BigQuery Links
Create link to GCP project
Choose export frequency (daily/streaming)

Migration Checklist

Before Migration

Create GA4 property
Document current UA goals and events
Plan UA → GA4 event mapping

Implementation

Implement GA4 code (gtag.js or GTM)
Configure basic events
Implement e-commerce tracking (if applicable)
Create conversions

After Migration

Compare UA and GA4 data (during overlap period)
Configure reports and dashboards
Connect to Google Ads and Search Console
Consider BigQuery export

Summary

Migration from UA to GA4 is not just a code change - it’s a change in how you think about analytics:

Event-centric - everything is an event
User-centric - tracking users, not sessions
Privacy-first - Consent Mode, cookieless tracking
ML-powered - predictive analytics, modeling

GA4 offers more capabilities than UA, but requires learning a new interface and data model.

Sources

Google Analytics Help - Set up Analytics for a website https://support.google.com/analytics/answer/9304153
Google Analytics Help - GA4 recommended events https://support.google.com/analytics/answer/9267735
Google Developers - GA4 Ecommerce https://developers.google.com/analytics/devguides/collection/ga4/ecommerce
Google Analytics Help - UA sunset https://support.google.com/analytics/answer/11583528
Google Tag Manager - GA4 Configuration tag https://support.google.com/tagmanager/answer/9442095