Why Google Ads, Meta and GA4 Never Agree (and Which Number to Trust)

Oct 9

Google Ads says you got 120 conversions last month. Meta says 95. GA4 says 140 total, but credits Google with 60 and Meta with 30. Your Shopify or CRM says 110.

Which number is right? Usually none of them, and all of them. Each tool measures something different. Once you understand why they disagree, you can stop arguing about the numbers and start making better budget decisions.

Why the Numbers Never Match

1. Different attribution models

Google Ads and GA4 can use data-driven attribution, which spreads credit across touchpoints. But each platform mostly credits itself. Meta credits Meta. Google Ads credits Google Ads. A customer who saw a Meta ad, then searched on Google and bought, can be counted as a conversion by both.

2. Different attribution windows

Meta's default counts conversions within 7 days of a click or 1 day of a view. Google Ads windows are set per conversion action and are often 30 days or more for clicks. GA4 has its own lookback settings. Different windows, different totals.

3. View-through conversions

Meta, YouTube, and Display can credit conversions to people who saw an ad but didn't click. GA4 is largely click-based. That alone can explain big gaps for social and video campaigns.

4. Conversion date vs. click date

Google Ads reports conversions on the date of the ad click. GA4 reports them on the date the conversion happened. Month-end comparisons often won't line up for that reason alone.

5. Modeled conversions

With consent banners, browser privacy features, and ad blockers, platforms can't observe every conversion. Google and Meta use modeling to estimate the missing ones. That's usually helpful, but it means platform numbers are partly estimates.

6. Cross-device and logged-in data

Google and Meta can connect journeys across devices for logged-in users. GA4 and your website analytics may see those as separate people.

7. Tracking errors

Then there are plain mistakes: duplicate tags, the same purchase counted by two conversion actions, missing deduplication between the Meta Pixel and Conversions API, broken UTMs, or a tag that fires on page load instead of a completed purchase. These are worth ruling out first.

Rule Out Tracking Problems First

Before you try to reconcile the differences, make sure the setup is sound:

Check that each platform's conversion actions fire once, on the right event.
Confirm that only valuable actions are set as primary conversions in Google Ads.
Make sure the Meta Pixel and Conversions API share event IDs for deduplication.
Audit UTM parameters so GA4 attributes traffic to the right source and medium.
Compare platform counts against backend orders or CRM records for a sample period.

Our Google Ads audit checklist covers more of these.

So Which Number Should You Trust?

Use each source for the job it's good at:

Your backend (Shopify, CRM, or order system) is the source of truth for total revenue, orders, and qualified leads.
Ad platforms are best for in-platform optimization: comparing campaigns, ads, and audiences against each other within the same platform. Their algorithms bid on these numbers.
GA4 is best for cross-channel journeys, on-site behavior, and a consistent (if imperfect) comparison across sources.

Better Ways to Judge Paid Media

Blended efficiency

Total revenue divided by total ad spend (often called MER, marketing efficiency ratio) tells you whether paid media is working overall, regardless of which platform claims credit.

New-customer metrics

Track new-customer revenue and cost per new customer. Platforms are very good at getting credit from returning customers who would have bought anyway.

Incrementality tests

Holdout tests, geo tests, and platform lift studies measure what would have happened without the ads. They take budget and planning, but they're the closest thing to a true answer.

Consistent reporting

Pick definitions and stick to them. A simple dashboard that shows backend results next to platform-reported results, with the same date ranges, ends most of the arguments.

The Bottom Line

Discrepancies are normal. Unexplained discrepancies aren't. If you can't explain why your numbers differ, start by fixing tracking, then build reporting around business results instead of platform claims.

Stonepath & Partners sets up and audits GA4, Google Tag Manager, Google Ads conversions, and the Meta Pixel and Conversions API as part of our paid media services and standalone audits. Let's talk if your numbers don't add up.

Jessica Lambert