This is why your numbers don’t line up…
First, understand that your Ads Manager reporting and GA4 will never match up. There are so many reasons for this. Meta and Google measure conversionsA conversion is counted whenever a website visitor performs an action that fires a standard event, custom event, or custom conversion. Examples of conversions include purchases, leads, content views, add to cart, and registrations. More differently, and they also have access to different information.
But there is one primary source of this that most advertisers miss.
Discrepancies
Advertisers may use UTM parameters with the hopes of having more reliable reporting and don’t understand why GA4 shows far fewer conversions from Facebook than does Ads Manager.
The assumption is that Ads Manager is somehow over reporting. After digging through events to confirm everything is set up properly, it’s assumed that Meta is doing something improper.
View-Through Conversions
The reason for this discrepancy is almost always found in your view-through conversions. By default, Ads Manager reports on conversions that happen within seven days of clicking or one day of viewing your ad, without clicking.
Your UTM parameters will be essentially worthless for those view-through conversions. These people didn’t click, so GA4 won’t think to give Facebook any credit.
You can get a breakdownBreakdown is a way to get insights into your ad performance related to time, delivery, action, or dynamic creative element. More of your conversions by attribution setting by using the Compare Attribution Settings feature.
I’m typically okay with view-through conversions because you can make the argument that they contributed. They just aren’t as valuable as click-through.
Editing the Attribution SettingAttribution is how Meta gives credit to an ad for a conversion. Your Attribution Setting determines how your ad will be delivered and the reporting attribution window. The default Attribution Setting is 7-day click and 1-day view, which means that anyone who converts within 7 days of clicking or 1 day of viewing your ad will be counted as a conversion. More
I tend to expect something around 10-15% of my conversions to be view-through. The problem would be if you have a high percentage of view-through conversions. This would be a sign that your results are getting inflated and should be corrected.
If that’s the case, change your attribution setting to clicks only — either 7-day click or 1-day click, depending on the type of conversion.
