Meta says the campaign produced 40 sales. Google Ads claims 25. GA4 shows 18 from paid traffic, and the store recorded 52 orders in total. Nobody is necessarily wrong. Each system is answering a different question.
Why they disagree
- Attribution. Each ad platform credits itself when its ad was anywhere in the path to purchase. GA4 assigns credit across channels. One sale can be claimed by both Meta and Google and counted once in GA4.
- View-through conversions. Meta counts people who saw an ad, didn’t click and bought later. GA4 only knows about visits.
- Attribution windows. A purchase a week after a click may count in one platform and not in another.
- Conversion date. Ad platforms usually report the sale on the day of the click. GA4 and your store report it on the day of the purchase.
- Consent and blocking. Cookie banners, browser privacy features and ad blockers remove some visits from GA4. Platforms fill part of the gap with modeled conversions.
- Different definitions. A conversion might be a purchase in one tool and a form view in another.
Which number to use
Use your store or CRM as the record of what was actually sold. It is the only system that sees every order and refund. Use GA4 to compare channels with each other, because it applies one set of rules to all of them. Use each ad platform’s own numbers to compare campaigns and ads inside that platform, not to add up revenue. Platform-reported revenue added together will usually exceed what the business took in.
One check survives all of this: total ad spend against total store revenue for the same period, tracked month to month.
When the gap means something is broken
- Paid conversions in GA4 fall to zero or near zero while orders continue.
- A platform reports more purchases than the store recorded in total.
- Conversion counts double overnight with no change in sales. This is often a duplicated tag after a site update.
- Order values in the platform don’t match order values in the store, which points to currency, tax or shipping being passed incorrectly.
- Paid traffic shows up in GA4 as direct or unassigned, which points to click IDs or UTM tags being lost, often after a redirect was added.
Some gap between an ad platform and GA4 is normal, and its size varies by business. A sudden change in the gap is what deserves attention.
When we report results, we say which system a number came from. In our PowerWash case study the return on ad spend is labeled as platform-reported for that reason. If your numbers don’t add up and you need to know which to trust, send us the details. This is the work described under Analytics & Intelligence.