In short: linking GA4 with Google Ads gives you three things — importable conversions, GA4 audiences in Ads and Ads cost in GA4 — and the rule that avoids disaster is one source per action: the Ads tag for primary conversions, GA4 for secondary ones, never both. The figures never match because of attribution, date, window and consent: compare trends, not totals.
Google Analytics 4 and Google Ads are two measurement systems that overlap and complement each other. Linking them well gives you audiences, conversions and context; linking them badly gives you duplicated conversions and endless arguments about "which figure is the right one". This lesson puts each in its place.
What is linking GA4 with Google Ads for?
Admin → Linked accounts → Google Analytics (GA4). With the link:
| From GA4 to Ads | From Ads to GA4 |
|---|---|
| GA4 key events importable as Ads conversions | Ads cost and click data in GA4's reports (ROAS by campaign alongside other channels) |
| GA4 audiences (built from all your site behaviour) available in Ads for remarketing and signals | Campaign/keyword dimensions in GA4 |
| Engagement metrics visible in Ads | — |
Measure conversions with GA4 or with the Ads tag?
Both work; pick one source per action so you don't duplicate:
| Criterion | Ads tag (direct / Tag Manager) | Import from GA4 |
|---|---|---|
| Attribution accuracy in Ads | Higher: the click and the conversion in the same system | Lower: it goes through GA4's model |
| Enhanced conversions | Yes, natively | Partial |
| Ease when GA4 already measures well | You have to tag separately | Immediate: mark the event as key and import it |
| Data from other channels | No | Yes (GA4 sees everything) |
| Delay | Almost immediate | Hours |
Recommendation: the Ads tag for your primary conversions (purchase, qualified lead) — maximum accuracy and enhanced conversions —; GA4 for secondary and engagement ones and for anything you need to look at alongside other channels. And never the same action through both routes as primary: it gets counted twice.
Why do GA4 and Google Ads show different figures?
| Difference | Google Ads | GA4 |
|---|---|---|
| Attribution | Only Ads clicks; data-driven among them | Every channel; last click or data-driven across channels |
| Date | The click date | The conversion date |
| Window | Each action's own (7-90 days) | GA4's model window |
| Consent | Ads modelling | GA4 modelling (a different one) |
| Counting | "One" or "every" per action | Every event |
| View-through | It can count | It doesn't |
If Ads says 50 and GA4 says 35, both can be right: Ads attributes to its click a sale that GA4 attributed to the email that came afterwards. Compare trends, not totals, and decide with the right tool: Ads to manage Ads, GA4 for the cross-channel picture.
How do you use GA4 audiences in Google Ads?
The biggest practical benefit of linking: GA4 builds audiences from all behaviour (pages, events, purchases, sequences, time) and publishes them into Ads automatically. Examples the Ads tag would not manage on its own: "viewed ≥ 3 products in category X without buying in 14 days", "users with a purchase ≥ €200", "abandoned the checkout at the payment step". They require GA4 to have Google signals enabled and the right consent.
What is the healthy GA4 and Ads setup?
- Link GA4 ↔ Ads; turn on auto-tagging.
- Primary conversions through the Ads tag (with enhanced conversions); secondary ones from GA4 where it suits. No duplication.
- GA4 audiences published into Ads for remarketing and signals.
- In GA4, the Ads cost data for the cross-channel report.
- A one-page document: what is measured where and why, so that nobody "fixes" the duplication by adding the two together.
💡 Ninja trick: reconciling what Google Ads attributes with what happens in the business works better per lead than in totals: Lead Rating stores, for every lead, its GCLID, its behaviour and its fate in the CRM — the reconciliation is not "50 against 35", it is "these 50 leads, one by one, which became customers". The argument about figures disappears once you look at rows.
What you should remember
- Linking gives you importable conversions, GA4 audiences in Ads and Ads cost in GA4.
- One source per action: the Ads tag for primary ones, GA4 for secondary; never both.
- They never match because of attribution, date, window, consent and counting: trends, not totals.
- GA4 audiences are the biggest practical benefit of the link.