Google Ads Says 40 Conversions. GA4 Says 24. Which One Is Lying?

This is the single most common question we get from business owners running their own ads, usually asked with a slightly panicked tone, because the obvious conclusion is that somebody has broken something. Normally nobody has. Here’s what’s really going on, how to work out which number to use for which decision, and when a mismatch does mean something’s wrong.

#Key summary

#The four reasons your numbers never match

Different dates. This one causes more confusion than anything else. Google Ads reports a conversion against the date of the click that led to it. GA4 reports it against the date the conversion actually happened. Someone clicks your ad on 28 July and buys on 3 August. Google Ads puts that sale in July. GA4 puts it in August.

For a business with a short sales cycle this barely registers. For anything with a considered purchase, it means your monthly reports will never line up, and the gap will look worst at the start and end of each month.

Different attribution. Google Ads wants to know whether Google Ads deserves credit. GA4 wants to know how all your channels combine. If a customer clicks a Facebook ad, then a Google ad, then arrives via organic search and buys, Google Ads will claim that conversion. GA4 will share the credit around. Neither is wrong. They’re answering different questions.

Different scope. Google Ads reports on Google Ads. That’s it. GA4 sees everything, including the direct traffic, the email click and the customer who typed your name in because they saw your van.

Different counting rules. Google Ads can count multiple conversions from a single click if you’ve set it up that way. GA4 counts events. Two products bought in one order might be one conversion in one system and two in the other.

#What actually changed with attribution models

If you’ve been running ads for a while you may remember choosing between first click, linear, time decay and position-based models. Those are gone. Google removed all four from GA4 and Google Ads, with the full sunset completing in September 2023, and GA4’s documentation confirms they’ve been unavailable since November 2023.

What’s left is data-driven attribution, which is now the default multi-touch model, and last click.

A lot of small businesses never noticed this happen, which means they’re sitting on reporting habits built around a model that no longer exists. If you have a spreadsheet comparing this year to a year when you were using position-based attribution, that comparison isn’t valid and hasn’t been for a while.

Data-driven attribution works out credit from your own conversion paths rather than applying a fixed rule. It’s better, and it has one practical consequence worth knowing: your numbers can shift without you changing anything, because the model is learning from new data. That’s a feature, and it’s also why chasing small week-to-week movements is a waste of your afternoon.

#Which number should you actually use

Use Google Ads conversions when you’re making decisions inside Google Ads. Bidding, budget allocation between campaigns, which keywords to pause. The platform optimises against its own numbers, so managing it against a different set creates a conflict you’ll lose.

Use GA4 when you’re deciding how much to spend on Google Ads versus everything else. GA4 is the only place that sees your whole picture, so it’s the only place that can honestly tell you whether paid search is pulling its weight against email, organic and social.

Use your actual sales data when the two disagree in a way that matters. This is the step almost everyone skips. Your accounting system knows what you really sold. If Google Ads claims 40 conversions, GA4 claims 24 and your invoicing system shows 19 new customers, that third number is the one your business runs on.

#When the gap does mean something’s broken

A stable gap is fine. A gap that suddenly changes size is the signal worth acting on.

If your GA4 conversions drop sharply while Google Ads holds steady, suspect your tracking first. Consent banners, a site update that stripped the tag, or a new checkout flow are the usual culprits. Australian sites adding consent management have been a common cause of exactly this pattern.

If Google Ads conversions jump while GA4 stays flat, check whether someone changed your conversion actions, added a new one, or switched something to count every conversion rather than one per click.

If both drop together, that’s more likely to be real. Look at your traffic before you look at your tracking.

The practical version of this: write down what your normal gap looks like as a percentage. Check it monthly. You’re monitoring the relationship, not the raw numbers.

#Getting your baseline honest

Most small business accounts we open have at least one of these problems. Until they’re fixed no attribution discussion is worth having.

Duplicate conversion tracking, where a purchase fires through both Google Tag and GA4 import, so everything is counted twice.

Conversion actions counting the wrong thing. Most often a thank-you page view that also gets hit by people refreshing, or a form submission that counts before validation.

Micro-conversions set as primary, so newsletter signups sit in the same column as sales and your cost per conversion looks wonderful while your revenue doesn’t move.

No offline conversion import, which matters enormously for service businesses where the sale happens on the phone. If you’re a trade or a clinic, Google Ads is optimising against form fills while your money comes from bookings it can’t see.

Fix those four and your reporting problem usually turns out to have been a tracking problem.

#Frequently asked questions

#What’s a normal difference between Google Ads and GA4?

Somewhere between 10 and 30% is typical, with Google Ads usually reporting higher. Longer sales cycles widen it. What matters is whether your gap is stable, not what it is.

#Which attribution model should I use in GA4?

Data-driven, in almost every case. Last click is worth looking at as a comparison when you want to understand what’s closing sales rather than what’s starting them, but it undervalues everything at the top of your funnel.

#Why did my conversion numbers change when I didn’t change anything?

Data-driven attribution recalculates as it gets more data, so some movement is normal. Conversions also get attributed back to earlier click dates in Google Ads, which means recent days keep filling in for a while. Don’t judge the last week until it’s settled.

#Should I trust Google Ads conversions at all?

Yes, for what they’re for. They’re the right input for optimising Google Ads. They’re the wrong input for deciding your total marketing budget, because Google Ads has an obvious interest in the answer.

#Do I need both GA4 and Google Ads conversion tracking?

Generally yes, but avoid importing GA4 conversions into Google Ads while also running Google Ads tags for the same actions. That’s the duplicate counting problem and it’s extremely common.

#The short version

Your platforms aren’t lying to you. They’re answering different questions and you’ve been reading their answers as though they were the same question.

Pick the right number for the decision in front of you. Watch the gap rather than the raw figures. And once a year, check what your accounting system says against what your ad platforms claim, because that comparison tells you more than any attribution model will.

If your numbers have gone somewhere strange and you can’t work out whether it’s tracking or reality, that’s something we diagnose quickly as part of our Google Ads work, or walk through step-by-step in our training program.

This guide is written by Hedgehog, a DIY digital marketing consultancy specialising in small and medium businesses in Australia. We offer digital marketing consulting, coaching and training.