Google Analytics 4 Event Tracking

Overview

Google Analytics 4 uses an event-based data model where every interaction is captured as an event with associated parameters. Unlike Universal Analytics' Category/Action/Label structure, GA4 events are flat with flexible parameter attachments, offering greater analytical flexibility.

Event Types in GA4

Automatically Collected Events

GA4 captures these without configuration:

Enhanced Measurement Events

Enabled in data stream settings:

Recommended Events

Google's predefined events for common use cases:

Custom Events

Create events for business-specific interactions:

Event Implementation

gtag.js Syntax

gtag('event', 'event_name', {
  'parameter1': 'value1',
  'parameter2': 'value2'
});

Google Tag Manager

1. Create a GA4 Event tag
2. Set the Configuration Tag to your GA4 config
3. Enter the Event Name
4. Add Event Parameters from GTM variables
5. Set appropriate trigger

Data Layer Push

dataLayer.push({
  'event': 'add_to_cart',
  'ecommerce': {
    'currency': 'USD',
    'value': 79.99,
    'items': [{
      'item_id': 'SKU-12345',
      'item_name': 'Wireless Headphones',
      'price': 79.99,
      'quantity': 1
    }]
  }
});

Core Events Catalog

Ecommerce Events

view_item_list

gtag('event', 'view_item_list', {
  item_list_id: 'category_electronics',
  item_list_name: 'Electronics',
  items: [
    {
      item_id: 'SKU-12345',
      item_name: 'Wireless Headphones',
      index: 0,
      price: 79.99
    },
    {
      item_id: 'SKU-67890',
      item_name: 'Bluetooth Speaker',
      index: 1,
      price: 49.99
    }
  ]
});

add_to_cart

gtag('event', 'add_to_cart', {
  currency: 'USD',
  value: 79.99,
  items: [{
    item_id: 'SKU-12345',
    item_name: 'Wireless Headphones',
    item_brand: 'AudioTech',
    item_category: 'Electronics',
    price: 79.99,
    quantity: 1
  }]
});

purchase

gtag('event', 'purchase', {
  transaction_id: 'ORD-98765',
  value: 156.96,
  tax: 8.00,
  shipping: 5.99,
  currency: 'USD',
  coupon: 'SUMMER10',
  items: [{
    item_id: 'SKU-12345',
    item_name: 'Wireless Headphones',
    price: 79.99,
    quantity: 1,
    coupon: 'SUMMER10'
  }]
});

Engagement Events

scroll_depth (custom)

// Track granular scroll milestones
gtag('event', 'scroll_depth', {
  percent_scrolled: 50,
  page_location: window.location.href
});

video_engagement (custom)

gtag('event', 'video_engagement', {
  video_title: 'Product Demo',
  video_provider: 'vimeo',
  video_percent: 75,
  video_current_time: 120,
  video_duration: 160
});

time_on_page (custom)

gtag('event', 'engaged_time', {
  engagement_time_msec: 60000,
  page_location: window.location.href
});

Lead Generation Events

generate_lead

gtag('event', 'generate_lead', {
  currency: 'USD',
  value: 100,  // Lead value
  lead_source: 'contact_form'
});

sign_up

gtag('event', 'sign_up', {
  method: 'email'  // or 'google', 'facebook'
});

Search Events

search

gtag('event', 'search', {
  search_term: 'wireless headphones',
  search_results_count: 24
});

Event Parameters

Standard Parameters

Custom Parameters

GA4 allows up to 25 custom event parameters per event:

gtag('event', 'custom_event', {
  custom_param_1: 'value1',
  custom_param_2: 123,
  custom_param_3: true
});

Register custom parameters as dimensions/metrics in GA4:

1. Go to Admin > Custom definitions
2. Click Create custom dimension or Create custom metric
3. Map the parameter name and scope

User Properties

Set persistent user-level attributes:

gtag('set', 'user_properties', {
  customer_tier: 'premium',
  subscription_status: 'active',
  lifetime_value: 1500
});

Naming Conventions

Event Names

• Use snake_case exclusively
• Maximum 40 characters
• Start with a letter
• Avoid reserved prefixes (ga_, google_, firebase_)
• Be descriptive but concise

Good examples:

• newsletter_subscribe
• pricing_table_click
• feature_onboarding_complete

Avoid:

• newsletterSubscribe (camelCase)
• Newsletter Subscribe (spaces)
• ga_custom_event (reserved prefix)

Parameter Names

• Use snake_case
• Maximum 40 characters
• Be consistent across events
• Match GA4 reserved parameter names where applicable

Conversion Configuration

Mark important events as conversions:

1. Go to Admin > Events
2. Toggle the Mark as conversion switch
3. Or go to Admin > Conversions > New conversion event

Conversion events unlock:

• Google Ads optimization
• Attribution analysis
• Funnel reporting

Event Limits and Quotas

QA and Validation

DebugView

1. Enable debug mode:

   • GTM Preview Mode (automatic)
   • GA Debugger extension
   • URL parameter: ?debug_mode=true
   • gtag: gtag('config', 'G-XXXXX', { debug_mode: true })

2. Open GA4 > Admin > DebugView

3. Trigger events on your site

4. Verify events appear with correct parameters

Real-Time Reports

1. Open GA4 > Reports > Real-time
2. Check Event count by Event name
3. Click events to view parameters
4. Verify parameter values are correct

Validation Checklist

Common Issues

Attribution Considerations

Engagement Time

GA4 uses engagement_time_msec for session quality:

// Custom engaged time tracking
let startTime = Date.now();
window.addEventListener('beforeunload', () => {
  const engagedTime = Date.now() - startTime;
  navigator.sendBeacon('/analytics', JSON.stringify({
    event: 'page_engagement',
    engagement_time_msec: engagedTime
  }));
});

Session Attribution

Events inherit session-level attribution from session_start. Ensure campaign parameters persist through the user journey:

• Store UTM parameters in session storage
• Include gclid in server-side events
• Verify attribution in BigQuery exports