Facebook says you made 150 sales. GA4 says 95. Your WooCommerce dashboard says 120. Which number is real? All three—and none of them. According to Meta, 65% of conversions start on one device and complete on another. GA4 cookies can not track those journeys. Facebook can.

The platforms will never match because they are measuring fundamentally different things with fundamentally different methods. The question is not which one is right—it is understanding why they differ and what you should actually trust.

Why Facebook Always Shows Higher Numbers

Facebook counts conversions GA4 literally cannot see. That is not a tracking error—it is architectural.

View-through conversions. Someone scrolls past your ad on Instagram, does not click, then Googles your product three days later and buys. Facebook credits that sale. GA4 has no idea the ad existed—it only saw the organic search. Meta default attribution includes 1-day view-through, meaning any conversion within 24 hours of seeing an ad (without clicking) gets counted.

Cross-device tracking. A user clicks your Facebook ad on mobile during lunch, then purchases from their laptop that evening. Facebook logged-in user graph connects these sessions. GA4 sees two separate anonymous visitors—one mobile bounce, one desktop conversion. 65% of conversions involve multiple devices, and GA4 misses the connection on most of them.

Attribution timing. Facebook attributes conversions to the day the ad was clicked. GA4 credits the day the conversion happened. Run a campaign on Monday, get sales Tuesday through Sunday, and your daily numbers will not align even if the totals eventually would.

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The Data Quality Problem Underneath

Before methodology differences even enter the picture, each platform receives different data. 31.5% of global users run ad blockers (Statista, 2024). That means Facebook pixel and GA4 tracking script are not even seeing the same visitors.

Safari Intelligent Tracking Prevention limits cookies to 7 days. Firefox Enhanced Tracking Protection blocks known trackers. Brave blocks everything. The browser privacy wars mean your WooCommerce store sends conversion events to Facebook and GA4, but a significant portion never arrive.

This creates compounding discrepancies:

• Facebook: Pixel blocked on 30%+ of visitors, but Conversions API can supplement server-side
• GA4: Script blocked on 30%+ of visitors, limited server-side options for most WordPress stores
• WooCommerce: Knows every order regardless of browser settings

When platforms receive different subsets of your actual traffic, discrepancies are not about attribution anymore—they are about incomplete data.

The 20% Rule: When Discrepancy Becomes a Problem

Industry benchmarks from Heath Media suggest under 20% discrepancy is acceptable—that is methodology. Above 20% indicates tracking problems that need diagnosis.

Mobile-heavy businesses see worse. Eaglytics analysis found up to 80% discrepancy in sectors where cross-device journeys dominate. If your customers research on phones and buy on desktops, expect Facebook to report significantly higher than GA4.

Signs your discrepancy is a tracking problem, not a methodology difference:

• WooCommerce shows more sales than both platforms combined—neither pixel is firing properly
• Facebook CAPI showing errors—server-side is not connecting
• GA4 conversions are flat while WooCommerce sales grow—tracking script blocked or misconfigured
• Thank-you page events missing—redirect issues eating your conversion data

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What You Should Actually Trust

Here is the uncomfortable truth: neither platform tells you how many sales you made. Your WooCommerce database does.

Use platform data for platform optimization. Facebook numbers tell you which campaigns Facebook thinks work. Use them to optimize Facebook campaigns. GA4 numbers show you traffic patterns and on-site behavior. Use them for that.

Use WooCommerce for business decisions. Revenue, profit, actual conversion rates—these come from your order database, not ad platform reporting. The platforms are incentivized to show their value; your WooCommerce database just counts money.

The paradigm shift: stop trying to reconcile platforms to match. Instead, ensure they receive consistent, complete data—then accept they will attribute differently.

How Server-Side Tracking Changes the Equation

Server-side tracking does not make Facebook and GA4 magically agree. They use different attribution models, and that will not change. But it solves the data quality problem underneath.

When both platforms receive identical conversion data from your server—same event, same timestamp, same user identifiers—any remaining discrepancy is purely about attribution philosophy. That is acceptable. What is not acceptable is platforms receiving different subsets of your conversions because browser-based tracking failed.

Transmute Engine™ captures purchase events directly from WooCommerce hooks, then routes identical data to Facebook CAPI, GA4 Measurement Protocol, and any other destination you configure. The event fires once, server-side, bypassing ad blockers and browser restrictions entirely. Both platforms see the same conversion. They attribute it differently—but at least they are attributing the same sales.

Key Takeaways

• 65% of conversions cross devices—Facebook tracks these, GA4 cookies mostly do not
• View-through conversions inflate Facebook numbers by design; GA4 can not measure ad views
• 31.5% ad blocker usage means platforms receive different visitor subsets before attribution even starts
• Under 20% discrepancy = normal methodology differences; above 20% = investigate tracking
• WooCommerce orders are your source of truth—platforms are for optimization, not revenue reporting
• Server-side tracking ensures consistent data to all platforms, making discrepancies purely methodological

Ready to send consistent conversion data to all your platforms? See how Transmute Engine works.