Why Are GA4 and Google Ads Numbers Different?
Same month, same campaign: GA4 says 40 conversions, Google Ads says 55. The first reaction is usually “one of them is broken”. Usually both are right — they just aren’t counting the same thing.
1. They date the conversion differently
This is the biggest cause. Google Ads records a conversion on the day of the click. GA4 records it on the day of the conversion.
So someone who clicks on Monday and buys on Thursday lands on Monday in Google Ads and on Thursday in GA4. Over short date ranges this alone produces a serious gap: the shorter the period you are judging, the larger the difference looks.
2. The attribution models differ
A customer arrives from an ad, later searches your brand on Google, then comes back directly and buys. Who gets credit?
Google Ads credits itself as long as it can see its own click. GA4 distributes credit across channels according to its own model. The same sale can end up with two different owners in two panels. Attribution model optimisation is exactly the work of setting that distribution.
3. Google Ads adds modelled conversions
Users who decline cookie consent can’t be measured directly. Google Ads fills that gap with a statistical estimate and reports it as a modelled conversion. GA4 doesn’t reflect that estimate the same way. Consent Mode setup is required for the modelling to work at all.
4. The counting rule may differ
In Google Ads a conversion action can count “every” or “one” per click. If it’s set to “every”, the same person submitting three forms becomes three conversions. GA4 aggregates its event differently. This setting is never reopened after setup in most accounts, and on its own it can produce a large gap.
5. You may not be measuring the same thing
The most commonly missed possibility: the conversion action in Google Ads and the key event in GA4 don’t point at the same thing. One counts “form submitted” while the other counts “thank-you page viewed”. Those produce different numbers because they are different things.
Which should you trust?
Google Ads when you’re making budget decisions, because the bidding algorithm runs on that data; deciding against a different number puts you at odds with what the system can see.
GA4 when you’re comparing channels, because it’s the only panel where organic, social and direct traffic sit side by side.
The real point isn’t which one is “correct” — it’s whether the gap is explainable. A steady gap with a known cause is fine; a gap that swings month to month means something is wrong in the setup.
Want me to look at your gap? I can compare the settings in both panels and work out which of these is producing it. Get in touch.
Frequently Asked Questions
How much of a difference is normal?
There’s no fixed threshold, but the gap should be explainable. If you can account for it with the five points above, it’s normal; if you can’t, the conversion tracking setup needs a look.
Will linking GA4 to Google Ads make the numbers match?
No. The link shares data; it doesn’t align counting rules. Matching them shouldn’t be the goal anyway.
Which one loses less data?
With enhanced conversions set up properly, the Google Ads side usually loses less. That doesn’t make GA4 wrong.
How do I work?
Work-hour packages
Tell me about your website and what you need on WhatsApp or by phone; we agree on a work block of somewhere between 5 and 40 hours and I start doing what is needed. What you get is not a calendar window — it is net working hours spent directly on your business. I can use 40 hours working three days straight, or deliberately spread it out and finish it over a year — whatever the work calls for. I do not spend my time estimating how long something will take, I spend it doing the work; every hour I spend has a lasting result on your site. We keep going for as long as you find it useful.
Why not monthly?
Is 40 hours a week?
On a fixed monthly fee both sides are watching the wrong thing: you watch a fixed cost, the other side watches how many more contracts like this they can line up. Working by the hour puts us both in front of the same thing — the real value of the work that got done. I know not having an upfront answer to "how much will this cost in total?" is the natural cost of this model. But instead of paying a fixed fee for months to a setup that is not producing results, you only pay for the qualified time spent on your work — and you see exactly where that time went, start to finish. That is why my clients keep coming back.