Why Google Ads and GA4 Show Different Conversion Numbers

If you run ads for clients, you have seen this before. Google Ads reports 50 conversions. GA4 reports 62. Your client asks "which number is right?" and you do not have a clean answer.

This is not a bug. It is not a mistake in your tracking setup. It is how these platforms are designed to work. Let me explain why the numbers differ, what each platform actually measures, and how to present the real picture to your clients.

If you want a step-by-step reconciliation process, see our guide on [how to reconcile Google Ads and GA4 numbers](/blog/how-to-reconcile-google-ads-and-ga4-numbers). For a deeper comparison, read [Google Ads vs GA4: which numbers should you trust](/blog/google-ads-vs-ga4-which-numbers-should-you-trust).

How Google Ads Counts Conversions

Google Ads uses its own attribution model. When someone clicks a Google ad and converts within the attribution window (usually 30 days), Google counts that as a conversion. Even if the person also clicked a Facebook ad, an email link, or came back organically before converting.

Google Ads also uses view-through conversions. If someone saw your ad (did not click) and later converted, Google can count that too.

The result: Google Ads tends to overclaim conversions compared to what actually happened on your website. We covered the [real cost of trusting these platform-reported numbers](/blog/real-cost-of-trusting-platform-reported-conversions) in a separate analysis.

Why Google Ads Numbers Are Inflated

Three specific things inflate Google Ads conversion numbers:

Attribution overlap. Most customers interact with multiple channels before converting. They might click a Google ad, see a Facebook ad, open an email, then convert. Google Ads claims this conversion. So does Meta Ads. GA4 counts it once.

View-through conversions. Google Ads counts conversions from people who saw an ad but did not click. If someone sees your display ad and converts the next day through organic search, Google claims credit. GA4 does not distinguish between ad viewers and everyone else.

Conversion window. Google Ads uses a 30-day click window and a 1-day view window by default. If someone clicks a Google ad and converts 25 days later through a different channel, Google still claims it. GA4 does not care about attribution windows — it records events as they happen.

A Real Example

A user clicks your Google ad for "running shoes" on June 1. They browse but do not buy. On June 15, they see your Facebook ad, click it, and buy the shoes for ₹5,000.

• Google Ads counts this as a conversion (within 30-day window)
• Meta Ads counts this as a conversion (within 7-day window)
• GA4 counts this as one conversion (the purchase happened)

Three platforms, one actual purchase, but two platforms claiming credit. This is why the numbers never match.

How GA4 Counts Conversions

GA4 tracks what happens on your website. When someone completes a conversion event (purchase, form submit, sign up), GA4 counts it. GA4 does not care which ad platform brought the person. It just records what happened.

GA4 is closer to ground truth because it tracks actual website events, not platform-attributed conversions.

Why GA4 Is More Reliable

GA4 has no incentive to inflate numbers. Google Ads wants you to spend more — more conversions means better ROAS means you increase budget. Meta Ads wants the same. Both platforms benefit from claiming more conversions.

GA4 does not sell ads. It does not care which platform brought the visitor. It just records what happened on your website. That makes it the most neutral, accurate source.

This does not mean GA4 is perfect. GA4 can miss conversions if tracking code is broken, if users block cookies, or if events are not configured correctly. But when GA4 is set up properly, it is the most reliable number you have.

When GA4 Might Be Wrong

GA4 is not always accurate. Here is when to question GA4 numbers:

• GA4 shows zero conversions but platforms show conversions — usually means the GA4 tracking code is broken or missing from conversion pages
• GA4 shows more conversions than both platforms — could indicate duplicate event tracking or bot traffic
• GA4 numbers suddenly drop — check if someone changed the conversion event settings or if the tracking code was modified

Always verify GA4 setup before using it as your benchmark. Use Google Tag Assistant to confirm the GA4 tag fires on all conversion pages.

The Real Numbers

Based on data from agencies using ADsHisaab:

• Google Ads overclaims by approximately 10.7% compared to GA4 on average
• Meta Ads overclaims by approximately 22.1% compared to GA4 on average

This means if GA4 shows 100 conversions, Google Ads will typically show 107-112, and Meta Ads will show 118-125. We break down exactly [how much Meta Ads inflates your conversions](/blog/meta-ads-overclaims-how-much-is-facebook-inflating) in a dedicated analysis.

Why Meta Overclaims More Than Google

Meta Ads has a larger gap than Google Ads for three reasons:

Estimated conversions. Since iOS 14.5, Meta lost visibility into 60-70% of iOS users. Instead of showing fewer conversions, it estimates the missing ones using statistical modelling. GA4 does not estimate — it only counts what it can verify.

Aggressive view-through attribution. Meta counts view-through conversions within 1 day. If someone sees your Facebook ad and converts the next day through a different channel, Meta claims it.

7-day click window. Meta uses a 7-day click attribution window by default. Google Ads uses 30 days. This means Meta's click window is actually shorter, but Meta compensates with estimated conversions and more aggressive view-through attribution.

What Is a Normal Discrepancy?

Not all gaps are equal. Here is how to interpret the numbers:

• Google vs GA4 under 15%: Normal. Attribution overlap is working within expected ranges.
• Google vs GA4 above 25%: Investigate. Could be duplicate conversion tracking or view-through conversions inflating the count.
• Meta vs GA4 under 30%: Normal since iOS 14.5. Expected due to estimated conversions.
• Meta vs GA4 above 40%: Investigate. Could be conversion window settings or Meta's estimation model overcompensating.

Why This Matters for Your Agency

When your client sees different numbers across platforms, they question your data. They ask "which one is right?" and if you cannot answer clearly, they lose trust.

The solution is not to pick one platform and ignore the others. The solution is reconciliation. Show all three numbers side by side. Calculate the discrepancy. Use GA4 as the benchmark.

What Clients Actually Think

When your report shows only Google Ads numbers (150 conversions), and your client logs into GA4 and sees 132, they think one of three things:

1. "My agency is inflating numbers to look good"
2. "My agency does not understand the data"
3. "Something is broken in my tracking"

None of these are good. But if your report shows all three numbers side by side with the discrepancy percentage, the client thinks: "My agency understands why these differ and is being transparent."

Transparency builds trust. Hiding numbers destroys it.

The Right Way To Report

Show a table like this in every client report:

Below the table, add one line: "Google Ads and Meta Ads use attribution models that credit conversions differently. GA4 counts actual website events. The percentages show the expected gap."

This one table and one sentence eliminate 90% of client questions about mismatched numbers.

What You Should Do

1. Always use GA4 as your ground truth for conversion counts
2. Show clients the discrepancy percentages (Google vs GA4, Meta vs GA4)
3. Explain that platform numbers include attribution, GA4 tracks actual events
4. Set up GA4 correctly — verify the tag fires on all conversion pages
5. Automate this reconciliation instead of doing it manually every month

For a full reconciliation framework, read our [ad reconciliation explained guide](/blog/ad-reconciliation-explained-guide-for-agencies). If you need help setting up GA4 correctly first, see our [GA4 setup guide for accurate conversion tracking](/blog/setting-up-ga4-for-accurate-conversion-tracking).

Setting Up GA4 For Accuracy

GA4 is only accurate if it is set up correctly. Here is what to check:

Conversion events are marked correctly. In GA4, go to Admin > Events. Make sure your key actions (purchase, form_submit, sign_up) are marked as conversions. If they are not marked, GA4 will not count them.

GA4 tag is on all pages. Use Google Tag Assistant to verify the GA4 tag fires on every page, especially conversion pages (thank you pages, confirmation pages).

No duplicate events. If your GA4 tag fires twice on the same page, conversions will be double-counted. Check for duplicate tags in Google Tag Manager.

Cross-domain tracking is set up. If your conversion happens on a different domain (payment gateway, third-party form), GA4 needs cross-domain tracking to connect the sessions.

How To Calculate The Discrepancy

The formula is simple:

Discrepancy % = ((Platform Conversions - GA4 Conversions) / GA4 Conversions) x 100

Example: - Google Ads: 150 conversions - GA4: 132 conversions - Discrepancy: ((150 - 132) / 132) x 100 = 13.6%

Do the same for Meta Ads: - Meta Ads: 175 conversions - GA4: 132 conversions - Discrepancy: ((175 - 132) / 132) x 100 = 32.6%

If GA4 shows zero conversions, you cannot calculate a percentage (division by zero). Show "N/A" instead. Do not show 0% — that implies the numbers match perfectly.

If you are spending hours every month reconciling numbers in spreadsheets, there is a better way. ADsHisaab automates the entire process and delivers branded reports to your clients on schedule.

Try it free at adshisaab.com