Attribution windows, explained: why your two dashboards never agree

The question I get asked most after “is this working” is some version of: “why does Meta say we got 40 sales and GA4 says 22?” Both dashboards are usually telling the truth — they’re just using different rules to decide what counts.

The three settings that quietly change every number you see:

• Attribution window. Meta’s default is 7-day click, 1-day view — meaning a sale is credited to an ad if someone clicked it within 7 days, or even just saw it within 1 day, before buying. GA4 typically uses last-click, data-driven, or a much shorter window. Same sale, different rules, different owner.
• Click vs. view-through. A view-through conversion — someone saw the ad, didn’t click, bought later anyway — is real, but it’s also the easiest number for a platform to inflate. I always check what percentage of “conversions” are view-through before trusting a big jump.
• Cross-device tracking gaps. Someone sees an ad on their phone and buys on their laptop an hour later. Meta may credit it if identity resolution links the devices; GA4 might not see the connection at all.

None of this means the numbers are useless — it means you need one dashboard as the source of truth for budget decisions, and the rest as directional signals, not competing verdicts. Pick one, understand its rules, and stop trying to make two systems that count differently agree with each other.