Meta vs GA4 conversions: why don't the numbers match?

TL;DR

•  Meta and GA4 count different things, over different time windows, using different definitions of a conversion. A gap is normal.
• Meta's default setting credits a conversion within 7 days of a click or 1 day of a view. GA4 has no view-through equivalent for Meta, so those conversions are invisible to it.
•  GA4 only runs its machine learning attribution model once your property clears 400 conversions for that action and 20,000 conversions in total inside the lookback window (Google Analytics Help). Most small accounts sit below that and quietly report on last click.
•  Neither dashboard is your source of truth. Your CRM, your invoices and your booked jobs are.
• A gap of roughly 20% to 50% on paid social is ordinary. A gap of 95% usually means something is broken.

What is attribution, in plain English?

Attribution is the process of deciding which ad or channel gets credit for a sale or a lead. That's the whole idea. Every platform makes that decision using its own rules, and the rules disagree with each other.

Meta looks at people. It knows someone saw your ad on Instagram at 9am, clicked nothing, then came back two hours later on a laptop and bought.

GA4 looks at sessions and cookies on your website. It sees a laptop session with no obvious ad source, and files it under direct or organic.

Same purchase. Two different stories. Both dashboards are telling the truth as they understand it.

Why does Meta report more conversions than GA4?

Meta reports more because it counts conversions GA4 was never built to see, and it counts them on a longer clock. Four differences do most of the damage: view-through conversions, cross-device matching, the date a conversion gets filed under, and the way each system handles repeat actions by the same person.

View-throughs are the big one. Meta's default attribution setting credits a conversion that happens within 7 days of a click, or within 1 day of someone seeing the ad and not clicking (Meta Business Help Center). GA4 has no equivalent for a Meta impression. So if someone scrolls past your ad, thinks about it over lunch, then searches your business name and buys, Meta counts that as its win and GA4 records a purchase from organic search. Neither one is lying.

Then there's the date problem. Meta files the conversion under the day of the ad interaction. GA4 files it under the day the conversion actually happened. Run a report on a single Tuesday and the two will disagree even when every other setting matches.

 Is GA4 even using the model you think it is?

Probably not. GA4 shows a machine learning model by default (Google calls it DDA), but it only runs that model once your property has the volume to support it. Google's own documentation puts the bar at 400 conversions for the specific action and 20,000 conversions across all actions, inside the lookback window (Google Analytics Help). Below that, GA4 falls back to last click without making any fuss about it.

Most small businesses are nowhere near 20,000 conversions. So the GA4 report you're holding up against Meta is almost certainly a last click report, and last click by definition hands all the credit to the final touch. Paid social is rarely the final touch. It's the thing that put you on the shortlist three weeks earlier.

The lookback windows are worth knowing too. GA4 uses 30 days for acquisition events like first visit, and 90 days for other click-through key events (Google Analytics Help). Meta's default click window is 7 days. You're comparing a 7 day clock against a 90 day one and expecting the totals to agree.

 What is actually different between the two systems?

The short version is that they disagree on who is being counted, for how long, and on which calendar day. Here's the side by side.

 Does a gap mean my tracking is broken?

Not by itself. A gap of roughly 20% to 50% on paid social turns up in almost every account we look at, and it's a normal result of the differences above. What matters is the shape of the gap rather than the fact it exists.

Start worrying when GA4 shows almost nothing. If Meta reports 200 purchases and GA4 reports 4, you're looking at a pixel or a tag that stopped firing. The same applies when a steady gap suddenly triples in a week and your spend didn't change.

Signal loss is real, and it's partial. AppsFlyer reported in April 2025 that around 50% of users globally now consent to tracking on iOS, up about 10 points since Apple introduced the prompt in 2021. That's half the signal degraded, not all of it. Any agency telling you tracking is completely dead is selling you something.Which number should I trust?

Neither, as your final answer. Trust your bank account.

Count the outcomes you can hold: booked calls, signed jobs, invoices raised, orders sitting in your store admin. Those numbers don't care about attribution windows. Then give each dashboard the job it's good at.

Meta is the better tool for judging one ad against another, because it's the only system that saw the impression. GA4 is the better tool for judging channels against each other, because it's the only system that saw your website. Asking either one to settle the other's argument is how owners end up turning off campaigns that were working.

 How do I check whether the ads are working?

Compare total leads and total revenue against total ad spend for the same month, then ask whether the business moved. That single comparison survives every attribution argument, because it doesn't depend on either platform being right.

Five checks, in order:

1.  Pull your real numbers first. Leads in your CRM or inbox, jobs booked, revenue billed for the month.
2. Pull total ad spend for the same month from Meta.
3.  Ask the plain question: did the business get more of what it wanted for that money?
4. Ask new customers how they found you. It's crude and people misremember, but a pattern across 30 answers tells you something.
5. Run a holdout. Switch Meta off for two weeks and watch your total lead volume.

The holdout is the check most owners skip, and it's the one that answers the question. Two quiet weeks is cheap compared to a year of arguing with a dashboard.

FAQ

Q1) Which is more accurate, Meta or GA4?

Neither. They measure different things. Meta is more accurate about who saw and clicked your ad. GA4 is more accurate about what happened on your site. Your CRM beats both of them on money.

Q2 )What's a normal difference between Meta and GA4?

Around 20% to 50% on paid social campaigns, based on what we see across accounts. Above roughly 70% it's worth checking your pixel and your tags before you blame attribution.

Q3) Should I set my Meta attribution to 7-day click only?

You can, and the two dashboards will look closer together. It also removes view-through conversions from the numbers Meta reports back to you, which can make good awareness campaigns look weak. If you change it, keep it changed, so your month on month comparisons still mean something.

Q 4) Will the Conversions API fix the gap?

It closes part of it. Server side tracking recovers conversions that browser blocking loses, so the two platforms usually move closer. It won't remove view-through conversions or the difference in how each platform dates a conversion, so expect a gap to remain.

Q5) Why does GA4 label my Meta traffic as direct?

Usually missing UTM tags on the ad link, or a browser dropping the referrer when the in-app browser hands off to Safari or Chrome. Tag every Meta ad URL with UTM parameters and most of that traffic starts getting labeled correctly.

Q6) Can I make the two numbers match exactly?

No. Aim for a stable gap you can explain, and get suspicious when it changes shape.

Conclusion

The gap between Meta and GA4 is two systems answering two different questions on two different clocks. Once you know which question each one answers, both dashboards get easier to read and a lot less stressful. Pick your source of truth, hold your settings still, and judge the ads on whether the business actually grew.

What does your gap look like this month, and has anyone ever explained it to you?

 Get a free 15-minute tracking check

If your Meta and GA4 numbers are miles apart and nobody has told you why, we'll look at it for you. Get a free 15-minute tracking check at cal.id/mavixmarketing/strategy-call  and we'll tell you whether it's an attribution difference or something that's genuinely broken.