Quick answer: GA4 has no "Goals." You convert by marking an event as a Key Event (Google renamed "Conversions" to "Key Events" in GA4; in Google Ads, the imported ones are still called Conversions). Each UA goal type maps to a GA4 event: Destination → a page_view condition or custom event; Event → the matching GA4 event; Duration and Pages/Session goals have no native equivalent and must be rebuilt as custom events or audience triggers.
This is a spoke of the GA4 vs Universal Analytics guide. Getting this mapping wrong is the most common reason post-migration conversion counts look off — and it feeds straight into GA4 vs Google Ads conversion mismatches.
Key Events vs Conversions
The terminology shifted, which causes real confusion:
- Key Event — the GA4 term (since 2024) for an event you've flagged as important. This is what UA "Goals" became.
- Conversion — now primarily a Google Ads concept. When you import a GA4 Key Event into Ads, Ads treats it as a Conversion for bidding.
Mental model: you mark Key Events in GA4 → import them into Google Ads → they become Conversions used for optimization. Same underlying action, two names depending on which tool you're in.
Mapping each UA goal type
| UA goal type | What it did | GA4 replacement |
|---|---|---|
| Destination | Fired on reaching a URL (e.g. /thank-you) | Mark page_view as a Key Event with a page_location condition, or fire a custom event on that page and mark it. |
| Event | Fired on a GA event (category/action/label) | Use the equivalent GA4 event (e.g. generate_lead, file_download, a custom event) and mark it as a Key Event. |
| Duration | Session longer than X minutes | No native equivalent. Build a custom event via GTM (timer trigger) or create an Audience and trigger an event on membership. |
| Pages/Screens per session | More than X pages viewed | No native equivalent. Use a GTM counter or Audience-triggered event. |
| Smart Goals | ML-picked "best" sessions for Ads | Deprecated. Use real Key Events + Google Ads Smart Bidding instead. |
The clean cases are Destination and Event goals. Duration and Pages/Session goals were always weak proxies for intent — migration is a good moment to replace them with a real action (a form submit, a signup, a qualified scroll) rather than recreating a vanity threshold.
How to mark a Key Event
- Confirm the event exists. In GA4, open Admin → Events (or Reports → Engagement → Events) and verify the event is actually firing. If it isn't, you need to create it first — via enhanced measurement, a GA4 event in GTM, or Create event in Admin.
- Mark it. In Admin → Key events, click New key event and enter the exact event name, or toggle the event to "Mark as key event" in the Events list.
- Wait for data. Only events that fire after you mark them count as Key Events — it's not retroactive.
- Import to Google Ads if you bid on it: link GA4 to Ads, then import the Key Event as a conversion action. Avoid double-counting with an existing Ads tag for the same action.
Mistakes that break conversion data
- Marking a high-frequency event (like
page_viewwith no condition, orscroll) as a Key Event — every session "converts," and your rate becomes meaningless. - Counting method confusion. GA4 counts a Key Event on every occurrence; UA goals counted once per session. A purchase event firing twice = two conversions in GA4. De-dupe at the tag level.
- Double-counting purchases from a duplicated tag or SPA re-render — see Shopify double-counting.
- Expecting history. Marking a Key Event isn't retroactive, so week-one numbers look low.
- Mismatched Ads import, where GA4 and Ads track the same action separately, inflating Ads conversions — the root of many GA4 vs Ads mismatches.
Validate your Key Events before trusting them for bidding. The 25-point audit checklist covers conversion setup, or Snifflytics flags mismarked and double-counted key events automatically.
FAQ
What replaced Goals in GA4?
Key Events. You mark any event as a Key Event instead of configuring UA-style goal types. In Google Ads, imported Key Events are called Conversions.
What's the difference between a Key Event and a Conversion in GA4?
They're the same action named differently by tool: "Key Event" is the GA4 term; "Conversion" is the Google Ads term for an imported Key Event used in bidding.
How do I migrate a UA destination goal to GA4?
Mark page_view as a Key Event with a condition on the destination page's page_location, or fire a custom event on that page and mark that event.
Is marking a Key Event retroactive?
No. Only events that fire after you mark them count, so it takes time to accumulate data.
Why does GA4 show more conversions than UA did?
GA4 counts a Key Event on every occurrence, while UA goals counted once per session. If an event fires multiple times per session, GA4's count will be higher.