GA4 uses a 90-day attribution window. Google Ads uses 30 days. They’re measuring the same conversions with different rulers—and they’ll never match. That’s not a bug. It’s by design. Here’s why this happens and what WooCommerce store owners should actually focus on instead of chasing impossible alignment.
Google renamed GA4 “conversions” to “Key Events” in March 2024 specifically because “important events that were marked as conversions in Analytics were measured differently from how Google Ads conversions are measured, leading to discrepancies” (Google Analytics Help, 2025). The renaming was Google’s way of saying: stop expecting these numbers to match.
The Attribution Window Problem
Attribution windows determine how far back a platform looks to credit a conversion to an ad click or interaction. Here’s where the guaranteed mismatch originates:
Google Ads: 30-day default lookback window for clicks. A customer who clicked your ad 31 days ago and bought today? Google Ads doesn’t count that conversion.
GA4: 90-day default lookback window. That same customer who clicked 31 days ago? GA4 credits the conversion. Same sale, different attribution.
Facebook: 7-day click window, 1-day view window (Analytics Playbook, 2025). Even shorter—meaning Facebook misses conversions that both Google platforms would count.
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These aren’t settings you forgot to configure. They’re fundamental differences in how each platform defines success. A 45-day purchase journey appears in GA4 but vanishes from Google Ads reporting entirely.
Where The Numbers Actually Match
The only place where conversions will actually match between GA4 and Google Ads will be in the Advertising section of GA4 (Analytics Playbook, 2025). This specific section uses the same attribution methodology as Google Ads, creating alignment by design.
Everywhere else in GA4—the standard reports, the engagement metrics, the exploration tools—uses GA4’s native attribution. Same underlying data, different counting rules, different numbers.
This is why comparing your GA4 dashboard to your Google Ads dashboard produces confusion. You’re not looking at apples and oranges. You’re looking at the same apples counted by different people using different definitions of “apple.”
What “Key Events” Actually Means
Google’s March 2024 terminology change created its own confusion. Here’s the translation:
Key Event (GA4): An event you’ve marked as important in GA4—purchases, sign-ups, form submissions. Measured using GA4’s attribution model with 90-day default lookback. What GA4 used to call “conversions” before March 2024.
Conversion (GA4 Advertising Section): Data imported from or aligned with Google Ads. Measured using Google Ads attribution methodology. The only place in GA4 where numbers match Google Ads.
Conversion (Google Ads): Actions tracked through Google Ads conversion tracking. Measured using Google Ads attribution with 30-day default lookback.
Same word, three different meanings depending on where you see it. Google’s “fix” introduced new confusion while solving the original problem.
Cross-Device Complexity Makes It Worse
65% of conversions start on one device and complete on another (Meta/Facebook, 2024). A customer researches on their phone during lunch, adds to cart on their tablet that evening, and purchases on their laptop the next morning.
Each platform handles this differently:
- Google Ads attempts cross-device attribution for signed-in users
- GA4 uses Google signals for cross-device tracking (if enabled)
- Facebook relies on logged-in user matching
Different matching capabilities mean different conversion counts—even within identical attribution windows. The platforms aren’t seeing the same user journey.
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What WooCommerce Store Owners Should Do
Stop trying to make the numbers match. They won’t. Instead, focus on what actually matters:
1. Use WooCommerce Orders as Your Source of Truth
Your actual revenue lives in your WooCommerce orders database—not in any analytics platform. When GA4 says you had 100 purchase Key Events and Google Ads says 85 conversions, check WooCommerce. That’s the real number.
2. Track Trends, Not Absolute Numbers
If Google Ads conversions increase 20% month-over-month, that signal matters regardless of whether GA4 shows the same percentage. Consistent measurement within each platform reveals optimization opportunities even when cross-platform numbers diverge.
3. Ensure Consistent Data Goes to All Platforms
The discrepancy problem gets worse when platforms receive different data. If ad blockers prevent your Facebook Pixel from firing but GA4 captures the event, you’re comparing incomplete data sets. Server-side tracking ensures the same raw conversion data reaches every platform—making discrepancies purely about attribution methodology, not data gaps.
Transmute Engine™ addresses this by routing WooCommerce purchase events to GA4, Facebook CAPI, and Google Ads simultaneously from your own server. The platforms still use different attribution windows—that’s unavoidable—but at least they’re all working from identical source data.
4. Understand What Each Platform Shows You
GA4 shows the full customer journey across your site. Google Ads shows how your paid campaigns perform within its attribution model. Facebook shows its ad performance within its attribution model. None is “right”—they serve different analytical purposes.
The Real Problem: Data Gaps
Attribution differences are annoying but predictable. The bigger problem is data that never makes it to the platforms at all. Ad blockers blocking JavaScript tracking. Safari’s 7-day cookie limit breaking attribution. Consent rejection preventing tracking entirely.
When 30-40% of your conversions never get tracked, the GA4/Google Ads discrepancy becomes noise compared to the signal you’re missing entirely. Server-side tracking from your WooCommerce order hooks captures conversions regardless of browser restrictions—giving every platform complete data to attribute according to their own rules.
Key Takeaways
- GA4 and Google Ads use different attribution windows—90 days vs 30 days by default means permanent mismatch
- Only the Advertising section in GA4 will show numbers matching Google Ads conversions
- “Key Events” replaced “conversions” in GA4 specifically to clarify these are different measurements
- WooCommerce orders are your source of truth—not any analytics platform
- Track trends within each platform rather than chasing impossible cross-platform alignment
- Server-side tracking ensures consistent raw data—making discrepancies purely about attribution methodology
Key Events are tracked actions in GA4 that measure important business outcomes (formerly called “conversions” in GA4). Conversions in GA4 now refers specifically to data imported from Google Ads. Google made this naming change in March 2024 to clarify that GA4 measures events differently than Google Ads measures conversions.
Different attribution windows cause the mismatch. GA4 defaults to 90-day lookback while Google Ads defaults to 30 days. A customer who clicked your ad 45 days before purchasing shows as a Key Event in GA4 but not as a Google Ads conversion. This is by design, not an error.
Only the Advertising section in GA4 will match Google Ads conversion numbers. This is because the Advertising section uses the same attribution methodology as Google Ads, while the rest of GA4 reports use different attribution settings.
Neither platform tells the “true” story alone. GA4 shows user behavior across your site with longer attribution windows. Google Ads shows paid ad performance with its attribution model. Your WooCommerce orders are the actual source of truth for revenue—use them to validate both platforms.
Stop chasing matching numbers. Start building consistent data foundations. When every platform receives complete conversion data from your WooCommerce orders, attribution differences become a solvable analysis problem—not a data quality crisis.
