If your Google Analytics shows more sales or sign-ups than your actual sales system does, you are not alone. Double counting is the most common problem we find in GA4 setups. Here is why it happens and how to check for it.
How it happens
GA4 can record the same thing in more than one way. A purchase might be sent by your website code, and again by a tag in Google Tag Manager, and a third time by a plugin on your e-commerce platform. Each one thinks it is the only one. GA4 adds them all up.
The five-minute test
Go to your site and complete one test purchase or form submission. Then open GA4, go to Reports, then Realtime. Look at the event count for your conversion event. If one action shows as two or three events, you have found your problem.
Why it matters for your ads
Google Ads and Meta use these conversion numbers to decide where to spend your budget. If a conversion counts twice, they think a campaign is working twice as well as it is. You end up paying more for results that are not real.
The fix
Pick one source of truth for each conversion and remove the others. This sounds simple, but it usually means cleaning up Google Tag Manager and agreeing as a team on what counts. Our Google Analytics 4 page covers how we do this.