Google Ads Conversion Discrepancy GA4: Why Your Numbers Don’t Match and How to Fix It

It’s probably the most common headache I see when I sit down with a new eCommerce client here at my marketing agency in Melbourne. They’ll pull up their Google Ads dashboard, then flick over to their GA4 reports, and the numbers look like they’re from two different businesses.

Before you can even think about fixing it, you have to understand why it’s happening in the first place.

Why Your Google Ads And GA4 Conversions Don't Match Up

The core of the issue boils down to a simple fact: Google Ads and GA4 have fundamentally different jobs. I've spent years setting up tracking for countless eCommerce businesses, from those needing intricate Shopify development to those running on custom builds, and this distinction is always the starting point.

• Google Ads is a performance tool. Its entire purpose is to tell you if your ads are driving a specific outcome, like a sale. It’s all about direct impact.
• Google Analytics 4 is an analytics tool. Its mission is to map out the entire customer journey, capturing every touchpoint across all your marketing channels, paid or not.

This massive difference in purpose means they come with different default settings right out of the box, which is what creates these frustrating data gaps.

The "Every" vs "One" Conversion Count Setting

The first place I always look is the conversion counting setting inside Google Ads. This is the most frequent culprit. By default for some conversion types, Google Ads often counts just "One" conversion per ad click.

So, if a potential customer for a service business clicks your ad and fills out your contact form three times in a frenzy, Google Ads will proudly report one single conversion.

GA4, on the other hand, is just doing its job. It sees three distinct form submission events, so it dutifully records all three. This setting alone can instantly create a massive variance between your two reports. For eCommerce stores, you almost always want to count 'Every' purchase, but it's a setting that's easily missed.

I once worked with a Melbourne-based Shopify store selling custom gift boxes. Their Google Ads reported 50 "Leads" for the month, but GA4 was showing 100 "generate_lead" events. The problem was that sneaky "One" conversion setting in Ads. This 50% variance was completely skewing their Return On Ad Spend (ROAS) and made them want to pull the plug on what was actually a very profitable campaign.

Getting your head around this foundational difference is the crucial first step. Your data isn't broken; the two platforms are just speaking slightly different languages. My job is to help you translate.

If you've checked all the basic settings and your conversion counts are still miles apart, the next place I always look is attribution models and lookback windows. These two settings are responsible for a huge number of Google Ads conversion discrepancy with GA4 issues if they aren't on the same page.

Think of it like two referees watching the same game but with different rulebooks. Each platform wants to take credit for a sale, but they measure "credit" completely differently.

Google Ads, by default, gives itself a pretty generous 30-day window to claim a conversion after someone clicks an ad. That means if a person clicks your ad on day one and finally buys on day 29, Google Ads takes full credit. GA4, on the other hand, might be set to a much shorter window or be using a totally different model to decide who gets the prize.

Attribution Models: The Real Story Behind The Numbers

The attribution model is the specific rule that decides which touchpoint gets the credit for a conversion. Google Ads is laser-focused on its own world, giving priority to ad interactions above all else. But GA4 is designed to take a more holistic view, looking at every channel from organic search to email.

This is where the numbers really start to drift apart. I recently worked with a client whose Shopify store was showing 250 sales in their Google Ads account, but GA4 was only attributing 165 of those to the exact same campaign. That 34% drop wasn't a mistake; it was because GA4’s model was giving credit to organic search and social media touchpoints that happened after the initial ad click but before the purchase. You can explore how Australian businesses are tackling this very issue in more detail.

Key Takeaway: A customer's journey is rarely a straight line. They might click an ad, browse your store, leave, see a post from your Facebook ads agency campaign, and then come back through a Google search to finally buy. Google Ads will often credit the initial ad, while GA4 may credit the final search.

Don't Forget About View-Through Conversions

Another sneaky culprit is the view-through conversion. This happens when someone sees your ad (but doesn't click it) and then converts later on. Google Ads absolutely loves to count these by default, which can make your campaign performance look much stronger than it actually is.

GA4, however, generally ignores these impressions unless you specifically configure it to do otherwise. This setting alone can inflate your Google Ads numbers, creating a phantom lift that doesn't reflect true user engagement. Understanding the various types of marketing attribution software available can help shed light on these different reporting methods and why discrepancies pop up.

Auditing these settings is non-negotiable. Getting your lookback windows aligned and truly understanding which attribution model each platform is using will solve a massive percentage of discrepancy mysteries.

My Go-To Troubleshooting Checklist For Nailing Down Tracking

When the numbers don't add up, it's time to get methodical. Over the years, I've developed a go-to checklist that helps me diagnose the root cause of a Google Ads and GA4 conversion discrepancy for my eCommerce clients. This isn't just theory; it's the exact process I follow every time I see a mismatch.

The first place I look is always inside Google Ads, specifically at the conversion counting settings. You'd be amazed how often the problem comes down to the classic 'Every' vs. 'One' setting.

For an eCommerce store, you want to count 'Every' purchase. Simple. But if for some reason you were tracking a 'contact us' form on your Shopify site, you'd probably only want to count 'One' conversion per user. Getting this right solves a huge chunk of issues right off the bat.

Verify Your Tagging Setup

Next, I dive straight into Google Tag Manager (GTM). Think of GTM as the central nervous system for all your tracking, and even a tiny misconfiguration here can cause total chaos. I always use the Preview mode to run through a full user journey, from ad click to purchase, watching carefully to see which tags fire and in what order. This is a core part of the service we provide, whether it's for a client needing a WordPress developer or a full Shopify build.

Here’s what I’m specifically looking for:

• Correct Tag Firing: Are both the Google Ads conversion tag and the GA4 event tag firing on the purchase confirmation or 'thank you' page? They should be.
• No Duplicate Firing: Is a tag firing twice? This can happen if old, hard-coded tracking is still on the site while also being managed in GTM.
• GCLID Persistence: Is the Google Click Identifier (GCLID) being passed correctly in the URL throughout the user's session? If that little piece of code disappears, Google Ads loses its connection to the conversion.

A critical step in really deep troubleshooting is examining the network requests. This comprehensive guide to the Chrome HAR file is brilliant for understanding what data is actually being transmitted under the hood. It’s technical, but incredibly revealing.

This flowchart breaks down how the tracking process is supposed to work, from that initial ad click all the way to the final conversion credit in GA4.

As you can see, it shows how multiple factors, including lookback windows and attribution models, all play a role in whether a conversion actually gets credited.

Before diving deeper, here's a quick cheat sheet for the most common issues I run into.

Common Discrepancy Causes And Quick Fixes

This table covers the low-hanging fruit. If you've checked these and are still stuck, it's time to dig into the finer details.

Check The Often-Overlooked Details

If the tags and basic settings look good, I move on to the finer details that are so easy to miss. These might seem small, but I've seen them cause baffling discrepancies for national eCommerce brands.

I once had a client selling across Australia whose Google Ads account was set to Sydney time (AEST) while their GA4 property was on Perth time (AWST). That two-hour difference meant conversions happening late in the day were being recorded on different days in each platform, making their daily reports an absolute nightmare to reconcile.

Always, always double-check for mismatches in:

1. Timezones: Make sure Google Ads and GA4 are set to the exact same timezone your business operates in.
2. Currency: Verify that both platforms are reporting in the same currency (e.g., AUD).
3. Cross-Domain Tracking: If your checkout process happens on a different domain (like Shopify's checkout domain or a third-party payment gateway), ensure cross-domain tracking is set up correctly in GA4. If it's not, the user journey breaks, and you lose all attribution.

By methodically working through this checklist—from the high-level settings down to the tiny details of your GTM setup—you can almost always pinpoint exactly where your data is going wrong.

Aligning Your Platforms for True Data Harmony

Alright, diagnosing the problem is half the battle. Now it’s time to get your reporting back in line. The single best practice I recommend to all my eCommerce clients, from those needing Shopify development in Sydney to local Melbourne stores, is to make GA4 the definitive source of truth.

This isn't just about making the numbers match up nicely in a report. It's about feeding the Google Ads algorithm much higher-quality, consistent data—which is absolutely essential if you want smart bidding to actually work its magic.

Why GA4 Should Be Your Single Source of Truth

By importing your GA4 conversions directly into Google Ads, you force both platforms to look at the exact same data, measured in the exact same way. It's a simple strategy that cleans up your entire setup and makes your data infinitely more reliable for making those critical business decisions.

The benefit here is massive. You're not just fixing a reporting headache; you're actively improving the algorithm's ability to find you more customers. Better data in means smarter optimisation out, and that leads directly to a stronger Return On Ad Spend (ROAS).

When you let Google Ads and GA4 track conversions separately, you're essentially letting two different pilots fly the same plane. By making GA4 the lead pilot, you create one unified flight plan that leads to a much smoother journey and a far more predictable landing.

The Step-by-Step Import Process

Pulling your GA4 conversions into Google Ads is a surprisingly straightforward process, and it pays dividends almost immediately. It’s the final step that closes the loop between what users are doing on your site and how your ads are performing.

Here’s the high-level approach I always take:

1. Check Your Account Linking First: Before anything else, jump into the Admin section in GA4. Under 'Product Links', find 'Google Ads Links' and double-check that your accounts are properly connected. This is the bridge that lets all the data flow between them.
2. Flag Key Events as Conversions in GA4: Still in GA4, head to 'Admin' > 'Data display' > 'Events'. Find the key actions you want to track, like a purchase event, and simply flick the toggle to mark it as a conversion.
3. Import Those Conversions into Google Ads: Now, switch over to your Google Ads account. Go to 'Tools and Settings' > 'Measurement' > 'Conversions'. Hit the '+' button to add a new conversion action, choose 'Import', then 'Google Analytics 4 properties', and finally 'Web'. You'll see a neat list of the GA4 events you just flagged. Select the ones you need and click import.
4. Set the Imported Conversion to 'Primary': This is the crucial last step. After importing, find the new conversion action in your list. Click on it, go to 'Edit goal', and set its Action optimisation to 'Primary'. This tells Google Ads to actually use this conversion for its bidding algorithms and include it in your main reporting columns.

Here in the Australian digital marketing scene, one of the most common frustrations for eCommerce businesses in Melbourne is this exact discrepancy. I've seen countless cases where Google Ads, by default, might be misconfigured, while GA4 is busy tallying every single purchase. This alone can lead to reports showing up to 30-50% more conversions in GA4.

By importing your GA4 events and setting them as the primary source, you can often shrink that gap to under 10%. It’s worth taking a moment to dive deeper into the key reasons for these data discrepancies to really get your head around the issue.

This simple alignment creates a powerful, closed-loop system where your ad platform is optimising towards the exact same goals your analytics platform is measuring. Finally, some harmony.

Navigating Consent Mode and Unavoidable Data Delays

Sometimes, the discrepancy you're seeing isn't a technical glitch or a settings mismatch. It's often the direct result of modern privacy features and the simple, unavoidable reality of data processing lags.

Two of the biggest culprits I see causing confusion are Google Consent Mode v2 and the natural delay in how data populates across platforms.

Consent Mode is a huge one. It's Google's way of respecting user privacy by changing how its tags behave based on whether someone consents to tracking. If a user says no, Google uses sophisticated modelling to estimate the conversions you can no longer see directly. It's a clever solution, but it can absolutely lead to numbers that don't perfectly align between Google Ads and GA4, especially if your setup isn't dialled in.

The Reality of Data Processing Delays

Another factor that causes unnecessary panic is data latency. I've had clients call me first thing in the morning, worried because the numbers from yesterday are way off, only for them to magically align by the afternoon.

It’s so important to remember that Google Ads and GA4 don't update in real-time, or even at the same speed.

• Google Ads is faster: It usually processes and displays conversion data within a few hours.
• GA4 is slower: It can take a full 24 to 48 hours to completely process and finalise all its event data.

This processing gap means a conversion might pop up in your Google Ads report hours—or even a full day—before it's properly attributed and counted in GA4.

My advice here is simple: never, ever pull final performance reports for the previous day first thing in the morning. Give the systems at least 48 hours to catch up and let the data settle. This one habit will save you a ton of stress and stop you from making knee-jerk decisions based on incomplete information.

Modelled vs. Observed Conversions

When you combine Consent Mode with these data delays, you end up with a mix of "observed" conversions (from users who gave consent) and "modelled" conversions (estimated from users who didn't).

Because Google Ads and GA4 use slightly different algorithms and data sets for their modelling, the final numbers can vary. This is a core reason for a google ads conversion discrepancy ga4 that isn't tied to a technical bug. It's the new reality of measurement in a privacy-first world.

You're no longer comparing apples to apples; you're comparing a basket of real apples with a basket of incredibly well-estimated ones. Understanding this distinction is the key to trusting your data again.

So, What's the Path Forward?

We've dived deep into the rabbit hole, exploring everything from simple settings mismatches in Google Ads to the nitty-gritty of attribution models and Consent Mode. My aim was to pull back the curtain on the whole Google Ads vs. GA4 conversion discrepancy and give you a clear, actionable plan to get your data singing from the same hymn sheet.

If there’s one thing I want you to walk away with, it’s this: consistency is everything.

Establishing a Single Source of Truth

The most bulletproof strategy I’ve seen work time and time again for my eCommerce clients is to make GA4 the single, undisputed source of truth. By doing this, then importing those validated GA4 conversions directly into your Google Ads account, you create a powerful, closed-loop system.

This approach nails two critical goals:

• It cleans up your reporting: No more second-guessing which platform to trust. Your numbers will finally align.
• It fuels smarter bidding: You’re feeding the Google Ads algorithm higher-quality, more consistent data, which directly improves its ability to find you more customers and boost your ROAS.

Don't let data discrepancies derail your growth or shake your confidence. Taking control of your tracking setup means you can finally trust your numbers and make strategic decisions with certainty. The goal here is to create a unified measurement strategy that works for you, not against you.

When to Call in an Expert

Look, if you're managing a significant ad spend and this all feels a bit overwhelming, remember that getting an expert eye on your setup can save you thousands in wasted ad spend and lost opportunities. As a digital marketing agency in Melbourne, this is what we do all day, every day for eCommerce businesses across Australia. We live for untangling these exact kinds of data knots.

A flawed tracking setup is like navigating with a broken compass—you're moving, but you have no real idea if it's in the right direction. Fixing your tracking is the single most important step you can take to ensure your marketing budget is working as hard as it possibly can.

This isn't just about fixing a reporting bug; it's about building a rock-solid data foundation that will support your business's growth for years to come. Take the time to get this right, and you'll be well on your way to reliable, actionable conversion data you can actually bank on.

At Alpha Omega Digital, we are a marketing agency based in Melbourne, Australia but also service clients from Sydney, Brisbane, Newcastle, Perth, Adelaide, Darwin and Hobart. If you're a business with a paid ads budget of at least 3k a month, I'd love to offer you a low risk deal- get a month of paid ads management FREE. Apply now through our contact page.