Most Google Ads accounts are not properly connected to Google Analytics. Not in any meaningful way. The accounts exist side by side, data flows into both, and yet the linking that would let them actually inform each other has never been completed. This is not a niche technical problem. It is one of the most common gaps we see when auditing paid search accounts.
The consequences are not abstract. Advertisers who link their Google Ads or Google Marketing Platform accounts to Google Analytics are correlated with a 23% increase in conversions and a 10% reduction in cost per conversion. Those numbers come from Brainlabs' analysis of their client base, and while correlation is not causation, the direction of travel is clear. Better data visibility leads to better decisions.
What Account Linking Actually Does
When you link Google Ads to GA4, two things happen that matter for paid search performance. First, your Google Ads campaign data - impressions, clicks, cost - flows into GA4 automatically. You can then analyse paid traffic behaviour alongside every other channel, using GA4's session and engagement data to understand what happens after the click. Second, GA4 conversion events can be imported back into Google Ads and used as conversion actions that feed Smart Bidding.
That second point is where it gets interesting. Most accounts rely on the Google Ads conversion tag for their primary conversion tracking. There is nothing inherently wrong with that, but GA4 conversions give you additional signals - particularly for softer engagement events or micro-conversions that sit earlier in the funnel. When those feed into Smart Bidding, the algorithm has more data to work with. More data generally means better optimisation, especially in lower-volume campaigns where the primary conversion fires too infrequently to train the model properly.
The linking process itself takes around ten minutes inside the Google Ads account. Go to Tools, then Linked accounts, find Google Analytics, and connect the relevant GA4 property. You then choose which GA4 conversions to import into Google Ads. That is it. The fact that so many accounts have never done this is not a technical barrier problem - it is a setup process that gets skipped during account launches and never revisited.
Campaign Data Import: The Step Nobody Talks About
The second overlooked step is campaign data import, specifically importing cost data from Google Ads into GA4. If you have already linked the accounts properly, Google Ads cost data should populate automatically in GA4 under the Advertising reports. But for campaigns running through Google Marketing Platform - Display and Video 360, Campaign Manager 360, Search Ads 360 - you often need to configure the data import separately.
Why does this matter? Because without cost data in GA4, you cannot calculate return on ad spend or cost per acquisition at the session and user level inside the analytics platform. You can see conversions. You can see which campaigns drove them. But you cannot see what you paid for each one without toggling between GA4 and the Google Ads interface and doing the arithmetic manually. That friction means it rarely gets done, and decisions get made on incomplete information.
With cost data properly imported, GA4 becomes a genuine attribution workspace. You can build Looker Studio reports that show CPA by campaign, by channel, by landing page - all from a single data source. That changes how you review performance and how quickly you can identify where budget is being wasted.
Why This Matters for AI Campaigns Specifically
Performance Max and AI Max campaigns rely entirely on the conversion signals you provide. The algorithm has no other way to understand what a good outcome looks like. If your conversion tracking is thin - only tracking final form submissions, for example, with no earlier engagement signals - the model is working with limited information. This is especially problematic in lead generation where conversion volumes are inherently lower than in e-commerce.
Importing GA4 conversions into Google Ads and using them as secondary conversion actions gives the algorithm more touchpoints to learn from. A user who views a pricing page, downloads a brochure, and then returns to fill in a form has generated multiple signals. If only the final form submission feeds into Smart Bidding, the model cannot distinguish that high-intent path from a user who bounced after one page and somehow converted anyway. GA4 linking is part of how you give the algorithm a richer picture.
There is also a practical reporting benefit. When GA4 is properly linked and conversion data flows in both directions, you can cross-reference what Google Ads reports as converted with what GA4 records. Discrepancies between the two are common and worth investigating. Duplicate conversions, attribution window mismatches, and tag firing issues all show up when you look at both systems together. Without the link, you often would not know there was a problem.
What to Check in Your Own Account
Start in Google Ads under Tools and then Linked accounts. Check whether your GA4 property is linked. If it is, check which GA4 conversions are being imported and whether any are being used as primary or secondary conversion actions in your campaigns. Unlinking and relinking can sometimes resolve data gaps if the connection was set up a long time ago under an older Universal Analytics property.
In GA4, go to Advertising and check whether campaign data is populating. If you see gaps or missing cost metrics, the data import configuration may need revisiting. For accounts running spend through Search Ads 360 or Display and Video 360, check the linking settings for those platforms separately - they do not inherit the Google Ads link automatically.
Finally, look at your active conversion actions in Google Ads and review which ones are marked as primary. If you are running Performance Max or AI Max campaigns, consider whether you have enough secondary signals feeding into those campaigns to support the bidding model. Micro-conversions - phone number clicks, time on site thresholds, video views - are worth adding as secondary actions, and GA4 is often the easiest place to create and import them from.
A Small Setup Investment With Outsized Returns
The gap between accounts that have properly connected GA4 and Google Ads and those that have not is not really about technical sophistication. It is about whether anyone has taken the time to do a thorough setup review. Account launches move fast, measurement gets deprioritised, and basic configuration steps get deferred indefinitely.
A 23% improvement in conversions and a 10% reduction in cost per conversion are not trivial numbers. They suggest that the information flowing between these two platforms - when the connection is properly established - changes how campaigns are managed and how well they perform. Getting that setup right is not a project. It is an afternoon's work. Most accounts will find it overdue.