How to Set Up Key Events (Conversions) in GA4 the Right Way

Key Events vs Conversions in GA4

GA4 renamed "Conversions" to "Key Events" in 2024 to reduce confusion with Google Ads conversions. In GA4, a Key Event is simply an event you have marked as important by toggling it in the Events report. In Google Ads, a "Conversion" is a bidding signal imported from GA4 (or configured directly in Google Ads). These are related but distinct.

Step 1: Ensure the Event Is Being Collected

Before marking an event as a Key Event, verify it is actually arriving in GA4:

1. In GA4: Reports then Realtime — trigger the event on your website and check it appears
2. Or: Reports then Engagement then Events — check the event appears in the event list (may take 24 hours)

Never mark an event as a Key Event before confirming it fires correctly. If the event is missing or miscounting, fixing it after marking it as a conversion is much more complex.

Step 2: Mark the Event as a Key Event

1. In GA4: Admin then Events (under Data Display)
2. Find the event you want to mark (e.g. purchase, generate_lead)
3. Toggle "Mark as key event" to ON

This is all that is required within GA4. The event will now appear in the Conversions section of reports and will be available to import into Google Ads.

Which Events Should Be Key Events?

Mark as Key Events:

• Purchase / transaction completions
• Lead form submissions (real submissions, not button clicks)
• Phone call click events (if tracked)
• Trial sign-ups or free account registrations
• Quote requests

Do NOT mark as Key Events:

• session_start, first_visit, page_view — fires constantly and means nothing as a conversion
• Button clicks that do not confirm an action occurred (the form was submitted, not just the button was clicked)
• Scroll events or time-on-page thresholds as primary conversions

Step 3: Import to Google Ads

1. In Google Ads: Tools then Conversions
2. Click + New conversion action
3. Select "Import" then "Google Analytics 4 properties"
4. Select your GA4 property and choose the Key Events to import
5. Configure attribution window (recommended: 30-day click, 1-day view)

After import, the conversion will appear in Google Ads reporting within 24-48 hours.

Avoiding Double-Counting in Google Ads

The most common conversion tracking mistake in Google Ads is having both:

• A GA4-imported conversion for "Purchase"
• A Google Ads tag-based conversion for "Purchase"

Both will fire for the same event, doubling your reported conversions and misleading Smart Bidding. For each conversion action, use only ONE source. If using GA4 as the source, remove the equivalent Google Ads tag-based conversion action.

Step 4: Set Attribution Windows

GA4's default attribution model is data-driven with a 30-day lookback window. Align your Google Ads imported conversion's attribution window with your actual sales cycle:

• Impulse purchases (fashion, food): 7-day click window
• Considered purchases (software, B2B): 30-90 day click window
• Long consideration cycles: 90+ day window (maximum available is 90 days for most)

Summary

GA4 Key Events are the foundation of accurate conversion tracking and Smart Bidding optimisation. Verify events fire correctly before marking them, import to Google Ads carefully, and eliminate any double-counting between GA4-imported and tag-based conversions. This single step — done correctly — has more impact on Smart Bidding performance than almost any other configuration.

See our GA4 Setup & Audit service for conversion tracking review.

Need conversion tracking set up correctly? Contact Adslytics.