Google Analytics 4 (GA4) represents a fundamental shift in how Google approaches analytics, especially when it comes to event tracking.

If you're migrating from Universal Analytics (UA) or trying to understand the differences between the two systems, this guide will walk you through everything that's changed with events in GA4.

The Philosophy Shift: From Session-Based to Event-Based

The most significant change in GA4 is the underlying data model itself.

Universal Analytics Approach:

• Session-based: In UA, sessions were the primary container for user activity

• Hit types: Pageviews, events, transactions, and social interactions were different hit types

• Events were secondary: Events supplemented pageview data

GA4 Approach:

• Event-based: In GA4, everything is an event

• Unified model: Pageviews, clicks, form submissions, and purchases are all just different types of events

• Events are primary: Events are the foundation of all measurement

[IMAGE: UA vs GA4 Data Models] Description: A detailed comparison diagram showing the fundamental differences between UA and GA4 data models. Split the image into two sections with headers "Universal Analytics Model" and "GA4 Model". For the UA side, illustrate a hierarchical structure starting with "User" at the top, branching down to multiple "Sessions", and then each session containing different types of "Hits" (pageviews, events, transactions) shown as different colored icons or boxes. For the GA4 side, illustrate a flatter structure with "User" at the top, connected directly to multiple "Events" of different types, all represented as equal boxes with different labels but the same visual weight. Use connecting lines to show relationships, with UA showing a clear hierarchy while GA4 shows a more direct user-to-event relationship. Include small labels explaining key concepts and use Google Analytics' blue and green color palette with clean, professional design elements.

Event Structure: Category-Action-Label vs. Parameters

The way events are structured has been completely redesigned in GA4.

Universal Analytics Structure:

• Category: Object interacted with (required)

• Action: Type of interaction (required)

• Label: Additional information (optional)

• Value: Numeric value (optional)

Example UA event code:

1. ga('send', 'event', 'Video', 'Play', 'Homepage Hero Video', 30);

GA4 Structure:

• Event name: Single identifier for the event

• Parameters: Multiple key-value pairs providing context

Example GA4 event code:

2. gtag('event', 'video_play', {

3.   'video_title': 'Homepage Hero Video',

4.   'video_duration': 30,

5.   'video_percent': 0,

6.   'video_provider': 'YouTube'

7. });

[GUIDED DEMO: Translating UA Events to GA4] Video Description: A 5-minute screencast showing side-by-side code translation from Universal Analytics to GA4 format. The video starts with examples of common UA event code with category-action-label structure displayed on the left side of the screen. The cursor then moves to the right side where the equivalent GA4 code is built step by step, highlighting how each component maps over. The demonstration covers several different event types (click events, form submissions, video tracking, downloads) and shows how to preserve the same data points while adapting to GA4's parameter-based structure. The video includes clear cursor movements when typing out parameter names and values, with occasional pauses to emphasize important conversion concepts.

Automatic Event Collection: Manual vs. Enhanced Measurement

GA4 collects many events automatically that required manual setup in Universal Analytics.

Universal Analytics:

• Most events required custom setup

• Only pageviews were tracked automatically

• Required extensive GTM configuration or code

GA4 Enhanced Measurement:

GA4 automatically collects these events without any additional code:

• page_view: When a user visits a page

• scroll: When a user scrolls 90% of a page

• click: When a user clicks an outbound link

• video_start: When a user starts a YouTube video

• video_progress: When a user reaches video milestones

• video_complete: When a user finishes a video

• file_download: When a user downloads a file

• search: When a user performs an on-site search

[IMAGE: Enhanced Measurement Settings] Description: A detailed screenshot of the GA4 Enhanced Measurement settings panel. The image should display the GA4 Admin interface with the Data Stream settings open, focusing on the Enhanced Measurement section. Each automatic event type should be clearly visible with toggle switches next to them. Add visual highlights or arrows pointing to key features: a green highlight around the master toggle at the top, and individual highlights around each event type (page views, scrolls, outbound clicks, site search, video engagement, file downloads). Include the gear icon that opens additional configuration settings with a small inset showing the expanded settings panel for one of the event types (such as scroll or video engagement). The interface should be shown in light mode with Google's standard interface elements, showing the exact controls an admin would use to enable or disable each automatic event type. Text in the image should be clear and readable, capturing the exact labels used in the GA4 interface.

Event Limits: 500 vs. 5000

Event quotas have been significantly expanded in GA4.

Universal Analytics:

• Limited to 500 unique event category/action/label combinations per property

• Going over this limit resulted in event sampling

GA4:

• Up to 500 unique event names per property

• Up to 25 unique parameters per event

• Up to 50 user properties per GA4 property

• Parameters are not part of the event cardinality limit

Implementation Tip: While GA4 allows more events, it's still best practice to create a consistent naming strategy to avoid hitting limits and to make reporting easier.

Recommended Events vs. Custom Events

GA4 introduces a new concept of "recommended events" with predefined names and parameters.

Universal Analytics:

• All events were custom

• No standardized naming conventions

GA4 Event Types:

1. Automatically collected events: Collected for all properties with GA4

2. Enhanced measurement events: Easily enabled in settings

3. Recommended events: Events with predefined names/parameters for specific industries

4. Custom events: Your own events with custom names/parameters

[IMAGE: GA4 Event Types Hierarchy] Description: A visual hierarchy diagram illustrating the four types of GA4 events. Create a pyramid or tiered structure with 4 levels. At the bottom (widest section), show "Automatically Collected Events" with icons representing page_view, session_start, etc. Above that, show "Enhanced Measurement Events" with icons for scroll, click, file_download, etc. The third level should show "Recommended Events" with examples from e-commerce, travel, and gaming verticals. At the top (smallest section), show "Custom Events" with a note indicating these are user-defined. Use different colors for each level (perhaps darkest at the bottom, lightest at the top), with clean labels and small example text for each section. Add brief explanations of when each type should be used. The design should be clean and modern, following Google's Material Design principles with appropriate shadows and depth to indicate the hierarchy.

Event Naming Conventions

GA4 has specific naming conventions that differ from UA practices.

Universal Analytics:

• Used separate fields (category/action/label)

• No specific naming conventions

• Often used proper case with spaces: "Video Play"

GA4:

• Uses snake_case for event names: video_play

• Reserved event names for automatic/enhanced events

• Recommended event names for specific industries

Implementation Best Practice: When naming custom events in GA4, follow the snake_case pattern (lowercase with underscores) to maintain consistency with Google's built-in events.

Reporting Differences

The way you analyze event data has changed significantly in GA4.

Universal Analytics Reports:

• Events report in Behavior section

• Top Events, Event Flow, and Pages reports

• Custom reports for deeper analysis

GA4 Reports:

• Events report in Engagement section

• Events are integrated throughout all reports

• Exploration reports for custom analysis

• Real-time report shows events as they happen

[GUIDED DEMO: Finding Event Data in GA4] Video Description: A 3-minute screencast navigating through the GA4 interface to locate and analyze event data. The demonstration begins at the GA4 home screen and shows clear cursor movements to access the Events report under the Engagement section. The video then explores how to examine individual events, showing how to view parameters and user segments for specific events. It continues by demonstrating how to create an Exploration report focused on event data, showing the exact clicks needed to select dimensions, metrics, and visualization types. The demonstration ends with a brief look at the real-time report, showing how to verify events are firing correctly. Throughout the video, cursor movements are deliberate and clear, with slight pauses at key navigation points.

Event Parameter Limitations

GA4 has specific limitations for event parameters that didn't exist in UA.

Universal Analytics:

• Could use any values for category, action, and label

• Values were always available in reports

GA4:

• Maximum of 25 unique parameters per event

• Only 50 unique user properties per property

• Not all parameters automatically appear in reports

• Need to register custom parameters as custom dimensions

Implementation Tip: In GA4, register your most important parameters as custom dimensions to ensure they're available in reports and explorations.

Migration Strategy

If you're moving from UA to GA4, follow these steps for event migration:

1. Audit existing events: Document all UA events currently in use

2. Map to GA4 equivalents: Determine how each UA event translates to GA4

3. Use automatic events: Enable Enhanced Measurement for automatic collection

4. Implement recommended events: Follow Google's recommended naming where applicable

5. Create custom events: Develop custom events for unique business needs

6. Register custom dimensions: Set up custom dimensions for important parameters

7. Validate implementation: Use DebugView to verify events are firing correctly

8. Update reports and dashboards: Rebuild reports to use the new event structure

[IMAGE: Event Migration Mapping] Description: A comprehensive migration planning document/spreadsheet visualization showing how to map UA events to GA4 events. Design this as a detailed spreadsheet or planning document with multiple columns: "Universal Analytics Event" (showing category/action/label combinations), mapped to "GA4 Event Name" and "GA4 Parameters" columns. Include at least 10 example rows showing common events like button clicks, form submissions, video interactions, etc., and how they translate to the GA4 structure. For example, UA "Video/Play/Homepage Video" would map to GA4 "video_play" with parameters for video_title, video_provider, etc. Use alternating row colors for readability, column headers in Google blue, and include annotations or notes column with migration tips. The spreadsheet should look like a practical working document that analysts would actually use when planning a migration.

Analyzing User Journeys in GA4

The approach to analyzing user journeys has evolved in GA4.

Universal Analytics:

• Event Flow report showed event sequences

• Behavior Flow report for page sequences

• Limited ability to combine different interaction types

GA4:

• Path Exploration shows sequences of events, pages, or other dimensions

• Funnel Exploration for conversion paths

• Segment Overlap for understanding user groups

Implementation Tip: Create a consistent parameter strategy to better track user journeys. For example, add a "section" parameter to all events to identify where on your site the interaction occurred.

E-commerce Event Changes

E-commerce tracking has been completely redesigned in GA4.

Universal Analytics E-commerce:

• Separate e-commerce tracking code

• Dedicated e-commerce reports

• Enhanced e-commerce for detailed shopping behavior

GA4 E-commerce:

• Uses standard event model with specific e-commerce events

• Recommended events like view_item, add_to_cart, purchase

• Required parameters for items array with product details

[GUIDED DEMO: Implementing E-commerce Events in GA4] Video Description: A 5-minute technical walkthrough showing how to implement e-commerce event tracking in GA4. The screencast begins by showing the code structure for key e-commerce events (view_item, add_to_cart, purchase), with deliberate cursor movements highlighting the required parameters and formats. The demo then shows implementation through both direct code and Google Tag Manager, providing a side-by-side comparison of the two methods. Special attention is given to the items array structure, showing the proper format for multiple products. The video concludes with testing the implementation in DebugView and verifying the data appears correctly in the GA4 reports section.

Advantages of GA4's Event Model

While the transition requires work, GA4's event model offers significant advantages:

• More flexibility: Parameters provide richer context than the category/action/label structure

• Better cross-platform tracking: Same model works for web and apps

• Reduced implementation: Automatic collection eliminates common manual tracking

• Advanced analysis: Exploration tools provide deeper insights than UA reports

• Future-proof: Designed for a cookie-less future with privacy in mind

Common Event Migration Challenges

When migrating from UA to GA4, watch out for these common challenges:

• Event naming conflicts: Avoid using reserved event names for custom events

• Missing parameters: Failing to include critical parameters that were in UA labels

• Inconsistent implementation: Mixing approaches across different parts of your site

• Overlooking automatic events: Duplicating events that GA4 already collects

• Report misalignment: New reports don't match old UA reports due to structural differences

[IMAGE: GA4 Event Debugging] Description: Create a detailed view of the GA4 DebugView interface being used to troubleshoot event migration issues. Show a split-screen setup with browser developer tools console open on the left side (displaying JavaScript console logs with gtag event calls visible) and the GA4 DebugView panel on the right (showing real-time events being received). Include indicators pointing to common migration issues: 1) An event with an incorrect name format highlighted in red, 2) A missing parameter warning, 3) A duplicate event indicator, and 4) A successfully migrated event highlighted in green. Add annotations explaining each issue and how to fix it. The interface should look realistic with actual event code and DebugView feedback, resembling what a developer would see when debugging event implementation problems during migration.

Conclusion: Embracing the GA4 Event Model

The shift from UA to GA4 events represents a significant change in approach, but also brings powerful new capabilities for analysts and marketers.

While the migration requires effort, the investment pays off with more flexible tracking, deeper insights, and better preparedness for a privacy-focused future.

Rather than trying to force GA4 to work like Universal Analytics, embrace its new event-centric model to unlock its full potential.

Next Steps

Now that you understand the differences between UA and GA4 events, here are your next steps:

1. If you haven't migrated yet, follow our complete GA4 migration guide

2. Learn how to implement events through Google Tag Manager with our GTM Implementation Guide

3. Explore how to build advanced reports with our Building Custom Event Dashboards and Reports guide

Remember that GA4 is still evolving. Stay updated on new features and capabilities by following our blog or subscribing to our newsletter.