Quick answer: GA4 and Google Ads will almost never match exactly because they use different attribution models, different conversion windows, different deduplication logic, and different definitions of what counts as a conversion. A 5–15% gap is normal. A gap larger than 25% usually means a real configuration problem.
If you're seeing wildly different conversion numbers between Google Analytics 4 and Google Ads, this guide walks through every reason it happens and exactly how to diagnose which one is hitting you.
The 7 reasons GA4 and Google Ads report different conversion numbers
1. Different attribution models
Google Ads defaults to data-driven attribution for conversions reported inside the Ads UI. GA4 also defaults to data-driven, but the model uses a different lookback window and a different signal set. Even when both are "data-driven," they produce different credit allocations.
How to verify: In GA4, go to Admin → Attribution Settings → Reporting attribution model. In Google Ads, go to Tools → Measurement → Attribution → Settings. If the models are mismatched, you'll see persistent differences.
2. Different conversion windows
Google Ads' default click-through conversion window is 30 days. GA4's default lookback window is 30 days for "Acquisition" but 90 days for "All other events." A conversion that fires 45 days after the click will show up in GA4 but not in Google Ads' counts.
3. Time zone mismatch
GA4 and Google Ads use separate time zone settings. If your Google Ads account is set to PST and your GA4 property is set to EST, conversions that happen in the 3-hour window at the end of the day get bucketed into different dates. This causes systematic discrepancies in daily reports — and the daily totals will match over a 7-day window but never match for a single day.
4. Deduplication: "Conversions" vs "Key Events"
Since March 2024, GA4 renamed "Conversions" to "Key Events" for its own reporting, but kept a separate "Conversion" type that flows to Google Ads. A Key Event in GA4 won't necessarily show up as a conversion in Google Ads unless you've explicitly marked it as one. This is the single most common cause of "GA4 says I had 50 conversions, Google Ads says 12."
How to fix: In GA4, go to Admin → Events. For each event you want in Google Ads, toggle "Mark as Key Event" AND ensure the event is imported as a conversion in Google Ads (Tools → Measurement → Conversions → New conversion action → Import → GA4).
5. Cross-domain tracking not configured
If your funnel spans multiple domains (e.g., yourstore.com → checkout.stripe.com → thankyou.yourstore.com), GA4 will count the user as multiple sessions if cross-domain tracking isn't configured. Google Ads' click ID (gclid) follows the user across the journey. Result: Google Ads reports the conversion correctly; GA4 attributes the conversion to "direct" instead of paid search.
How to verify: Check Admin → Data Streams → your stream → Configure tag settings → Configure your domains. All domains in your funnel must be listed.
6. Enhanced Conversions misconfiguration
Enhanced Conversions for Google Ads sends hashed first-party data (email, phone) to recover conversions lost to cookie restrictions. If you have Enhanced Conversions on in Google Ads but the data isn't being sent correctly (missing parameter mappings, wrong field names), Google Ads can sometimes over-report conversions because it counts both the GA4-imported conversion and an enhanced conversion match.
7. Bot traffic and invalid clicks
Google Ads filters invalid clicks at the platform level — you don't pay for them and they don't show as conversions. GA4 has its own bot filtering, but it's separate and less aggressive. Bots that fire purchase events on your site will show up in GA4 but never in Google Ads, inflating your GA4 numbers.
How to diagnose your specific gap in 10 minutes
- Pull both reports for the same date range (use 7 days minimum to neutralize time zone effects)
- Compare conversion names first — are they the same conversion or different ones?
- If the names match, check your attribution model and lookback windows in both platforms
- Check the deduplication setting on the conversion action in Google Ads (Tools → Conversions → click the action → Conversion source)
- Compare totals over a longer window (30 days) — discrepancies should average out
When to worry vs when not to
Don't worry: A 5–15% gap is normal and expected. The platforms count things differently by design.
Do worry: Gaps over 25%, especially when one platform shows zero conversions for a campaign that the other shows hundreds.
Definitely fix it: When trend lines diverge — GA4 conversions going up while Google Ads conversions stay flat usually indicates a Google Ads import problem.
Audit your full GA4 setup automatically
The seven issues above are some of 100+ configuration checks a complete GA4 audit covers. Run a free Snifflytics audit to get a full report on your GA4 setup — including conversion configuration, attribution settings, cross-domain tracking, and the exact issues most likely causing your Google Ads mismatch.