Why Your GA4 and Google Ads Numbers Don’t Match

Here’s what I’m thinking: GA4 says 100 conversions. Google Ads says 150. You’ve probably been here. Staring at two dashboards, wondering which one is lying to you.

Neither is lying. They’re answering different questions.

Everyone explains why the numbers don’t match — attribution windows, conversion counting, cross-device tracking. We’ll cover that. But nobody tells you which number to trust for which decision. That’s the part that actually matters.

The Wrong Question

“Why don’t my numbers match?” is the wrong question. The platforms measure different things on purpose. They should report different numbers.

Google Ads measures its own influence. It only sees clicks and impressions within its ecosystem. That’s not a bug — it’s optimizing for Google Ads performance.

GA4 tries to measure everything. Cross-channel, all touchpoints, the whole customer journey. But it’s also missing data constantly — blocked cookies, denied consent, cross-device gaps without User-ID setup.

A 20-30% discrepancy? Normal. Expected. Built-in.

The right question: Which number do I use for which decision?

The 5 Reasons (Quick Version)

You’ve seen the listicles. Here’s the short version of why the numbers differ:

1. Attribution windows differ. Google Ads defaults to 30-day click, 1-day view-through. GA4 defaults to 90 days. If your sales cycle is 60 days and you’re running 30-day windows in Google Ads, you’re missing conversions.

2. Conversion counting differs. GA4 counts every conversion instance by default. Customer buys three times? Three conversions. Google Ads lets you choose: count one or count all. If these settings don’t match, neither will your numbers.

3. Click date vs conversion date. This is the one that confuses stakeholders most. Google Ads reports conversions on the date of the click. GA4 reports them on the date of the conversion.

User clicks May 1, converts May 5? Google Ads says May 1. GA4 says May 5. Both are correct. They’re just answering different questions.

4. Cross-device tracking differs. Google Ads uses Google Signals automatically — anyone logged into a Google product gets tracked across devices. GA4 needs User-ID setup to do the same thing. Without it, GA4 sees device A and device B as two different people.

5. Modeled conversions differ. When cookies are blocked or consent is denied, both platforms model what they can’t observe. But Google Ads applies additional modeling on top of what GA4 exports. More modeling = higher numbers.

Which Number to Trust When

Here’s the framework:

Use Google Ads numbers for:

  • Campaign optimization and bidding decisions
  • Evaluating Google Ads ROAS specifically
  • Anything where you need the platform’s data-driven attribution to improve performance
  • When you’re optimizing within Google Ads

Use GA4 numbers for:

  • Cross-channel budget allocation
  • Understanding the full customer journey
  • Board/executive reporting on total attribution
  • When you need a “neutral” view that doesn’t favor any single platform

Neither is “right.” They’re right for different things.

Google Ads tells you how Google Ads is performing. GA4 tries to tell you how everything is performing. Different questions, different answers.

The 30-Second Stakeholder Explanation

Your CMO asks: “Why does Google Ads say we got 150 conversions but GA4 says 100?”

Here’s your script:

“Google Ads counts conversions on the click date and only tracks its own ecosystem. GA4 counts on conversion date and tries to track everything. A 20-30% gap is normal. We use Google Ads data to optimize our ad spend and GA4 data to see the full picture across all channels.”

That’s it. Don’t overcomplicate it.

If they push back, the click date vs conversion date example usually lands: “If someone clicked our ad on the 1st and bought on the 5th, Google Ads records that sale on the 1st. GA4 records it on the 5th. Same sale, different reporting logic.”

What to Do About It

Stop trying to make the numbers match. They won’t. By design.

Instead:

  • Align your attribution windows across platforms where possible. If your sales cycle is 60 days, don’t run 30-day windows anywhere.
  • Check your conversion counting settings. Make sure “count one” vs “count every” is intentional, not accidental.
  • Wait 48+ hours before comparing. GA4 has processing lag that Google Ads doesn’t.
  • Use each platform for its strength. Google Ads for optimizing Google Ads. GA4 for the cross-channel view.

The discrepancy isn’t a problem to solve. It’s a feature to understand.

My Take

The platforms are never going to agree. They’re measuring different things for different purposes. Chasing a perfect match is wasted effort.

What actually matters: knowing which number answers the question you’re asking. Google Ads numbers for Google Ads decisions. GA4 numbers for cross-channel decisions.

Stop debugging the discrepancy. Start using the right number for the right question.