The short version: linking Google Ads with GA4 takes about ten minutes, but it only works if you do it from both sides, choose the right property and account, and then check your conversion data isn’t being counted twice. Most accounts I audit have the link switched on but the settings underneath are still wrong, which is worse than not linking at all because it looks fixed while quietly feeding you bad numbers.
Why this link matters more than people think
Google Ads tells you what you spent. Google Analytics tells you what people did once they landed on your site. Without the two talking to each other, you’re guessing which campaigns work based on click data and last-click assumptions inside Ads itself, which is a bit like judging a restaurant by how many people walked through the door rather than how many finished their meal and came back.
When it’s linked correctly, GA4 sends its behavioural data (session length, pages viewed, whether someone added to basket, whether they signed up) back into Google Ads, and you get to import those as conversions Ads can optimise towards. Get the link wrong and you either see nothing, see duplicate conversions, or see numbers that don’t match between the two platforms, which is the single most common support ticket I get asked about after “why has my traffic dropped.”
The actual step-by-step
Here’s what to do, in order. Skipping the order is where most people go wrong.
- Log into Google Ads with an account that has admin access, not standard access. This matters because linking is an admin-level action on both platforms.
- Go to Tools and Settings (the wrench icon), then under Setup click Linked accounts.
- Find Google Analytics (GA4) in the list and click Details.
- Click Link, then choose the correct GA4 property from the dropdown. If you manage multiple properties, double check you’re picking the one tied to the actual website running the ads, not a test property or an old one left over from a previous agency.
- Confirm the link. You’ll now see a “Linked” status against that property.
- Switch over to Google Analytics itself. Go to Admin, then under the Property column click Product Links, then Google Ads Links.
- You should see the link you just created appear here too. If it doesn’t show within a few minutes, refresh, because sometimes the two platforms take a moment to sync.
- Click into the link and turn on “Enable personalised advertising” and “Enable auto-tagging” if they’re not already on. Auto-tagging is the bit almost everyone forgets, and it’s the reason data doesn’t match between platforms.
- Go to Admin, then Events, then Key Events (this used to be called Conversions in the old GA4 interface, and some accounts still show it that way).
- Mark the events you want counted as conversions, things like purchase, sign_up, or generate_lead. Don’t mark everything.
- Back in Google Ads, go to Goals, then Conversions, then Summary, and click “New conversion action.” Choose Google Analytics 4 as the source.
- Import only the key events you marked in the step above. Give it a day or two, then check the numbers appearing in Ads match roughly what you see in GA4’s own reports.
That’s the whole process. Ten steps, maybe fifteen minutes if you’re not fumbling through menus. The failure point is almost never the linking itself, it’s step nine and eleven, deciding what counts as a conversion and making sure you’re not importing something you’re also tracking natively inside Ads.
The mistake that cost one client three months of wasted spend
I worked with an ecommerce client selling home fitness equipment who had Google Ads conversion tracking set up through the old gtag.js snippet directly on their thank you page, and separately had GA4 linked with purchase as a key event imported into Ads as a second conversion action. Both were live at the same time. Nobody had turned one off.
For three months, every purchase was being counted twice in Google Ads’ reporting. Their dashboard showed a return on ad spend of 6.2 to 1. The real number, once we stripped out the duplicate, was 3.1 to 1. They’d been about to double their monthly budget from £4,000 to £8,000 based on numbers that were literally twice as good as reality. If they’d made that call, they’d have burned through cash chasing a ROAS that didn’t exist.
This is the uncomfortable bit nobody likes to say out loud: linking Google Ads to Analytics is often sold as a “set it up once and forget it” job by agencies who bill for the initial setup and then move on. It isn’t. You need to check quarterly whether you’ve got duplicate conversion actions, whether a developer added a new tracking snippet without telling anyone, and whether the events you originally marked as key events still match what the business cares about six months later. The link doesn’t maintain itself, and most of the bad ROAS numbers I see in client accounts come from exactly this kind of silent duplication, not from bad targeting or weak ad copy.
Checking whether your setup is correct
Once you’ve linked the accounts, run this quick check:
- In GA4, go to Reports, then Acquisition, then Traffic Acquisition, and filter by Session source/medium. You should see google / cpc showing up as a source, with sessions and conversions attached to it.
- Compare the conversion count for google / cpc in GA4 against the conversion count showing in Google Ads for the same date range. They won’t match exactly because of different attribution windows and processing times, but they should be within roughly 5 to 10 percent of each other. If Ads is showing double what GA4 shows, you likely have a duplicate tracking issue like the one above.
- Check your landing pages are being recorded correctly in GA4 in the first place, because if the underlying page data is broken, the Ads link will just import broken numbers faster. This is worth checking separately, and I’ve written a full walkthrough on what to do when a landing page isn’t showing correctly in GA4 if your traffic looks right but your landing page reports look thin.
- Confirm your key events mean something to the business. I’ve seen accounts import “session_start” as a conversion, which is technically an event but tells you nothing about whether someone bought anything. If you’re unsure what qualifies as trackable in the first place, it’s worth reading through what counts as an event in Google Analytics before you decide what to import into Ads.
Permission problems that trip people up
This one’s boring but it stops more linkings than anything else: the person setting up the Google Ads side often isn’t the same person with admin rights on the GA4 side. I’ve sat on calls where a marketing manager has editor access to Ads but only viewer access to Analytics, which means the link button simply doesn’t appear for them. You need Administrator or Edit-level access on both platforms, granted by whoever owns each account.
If you’ve inherited an account from a previous agency or freelancer and you’re not sure who has admin rights on the Analytics side, this is worth sorting before you try anything else. I’ve written about the practical side of this in a piece on how to transfer a Google Analytics account safely without losing historic data, which covers exactly this handover problem. And if you’re being asked for a tracking ID or measurement ID and can’t find it, there’s a straightforward guide on where to find your Google Analytics tracking ID so you’re not hunting through menus for twenty minutes like most people do the first time.
What to do once it’s linked
Linking is the start, not the finish. Once your Ads and GA4 data are talking to each other, the actual work is deciding what you do with it. A few things worth doing in the first week:
- Set your imported conversions to “primary” status in Ads only for events that matter (purchases, qualified leads, bookings), and mark lower-value actions like newsletter signups as secondary so Google’s bidding algorithms don’t chase the wrong thing.
- Check your attribution model. GA4 defaults to data-driven attribution, which spreads credit across the customer journey rather than giving it all to the last click. This usually makes early-funnel campaigns look better than they did under old last-click models, which can be a shock if you’re used to Universal Analytics numbers.
- Give it two to three weeks of data before making budget decisions. I’ve seen people panic and pause campaigns three days after linking because the numbers “look worse,” when the numbers just look different because they’re being measured for the first time.
If you’re running Analytics alongside a wider SEO effort too, it’s worth thinking about how these two data sources sit together rather than as separate dashboards you check on different days. There’s a practical guide on using analytics tools alongside your SEO strategy that covers how to avoid drowning in reports once you’ve got multiple platforms feeding into each other.
A quick word on cost, because people ask
You don’t need to pay anyone to do the linking itself, it’s free and takes fifteen minutes if you follow the steps above. Where it makes sense to bring in help is the auditing side, checking whether your existing setup has duplicate conversions, wrong attribution settings, or key events that don’t reflect what the business sells. That’s a few hours of proper diagnostic work, not a big retainer, and if you want to see what that typically costs before you commit to anything, I’ve broken it down on the page about what an AI consultant costs, since a lot of the same audit work now overlaps with AI-assisted marketing setups.
Frequently asked questions
Do I need to link Google Ads to GA4, or is UA linking still relevant?
Universal Analytics stopped processing data in mid-2024, so if you’re setting anything up now, it needs to be GA4. Any old UA to Ads link is dead weight and can be removed.
Why does my Google Ads conversion count not match Google Analytics?
Small differences of 5 to 10 percent are normal because of different attribution windows and processing delays. Anything bigger, especially numbers roughly double, usually means you’re running duplicate conversion tracking, one native to Ads and one imported from GA4 for the same action.
How long after linking before I see accurate data?
Give it two to three weeks. The link itself activates within minutes, but conversion data needs a full sales or lead cycle to settle before you should trust it enough to change budgets.
Can I link one Google Ads account to multiple GA4 properties?
Yes, Google Ads supports linking to more than one GA4 property, which is useful if you run separate properties for different regions or brands. Just make sure each linked property is importing its own separate set of key events, so you’re not double counting across properties for the same customer action.
