Somebody notices that GA4 reports 240 conversions and Google Ads reports 310, and a meeting gets booked to find out which system is wrong.
Neither is. The two numbers are produced by different products, on different dates, under different attribution rules. They were never designed to match, and in March 2024 Google renamed things specifically to make that clearer — which, for a while, made it more confusing.
What changed on 21 March 2024
Google renamed conversions to key events in GA4. Platform-wide and permanent: admin toggles, report columns, API fields.
The reason was terminological hygiene. “Conversion” appeared in both GA4 and Google Ads, labelling related but genuinely different things, and practitioners lost hours debugging a discrepancy that was architectural rather than a bug. Reserving conversion for Google Ads made the boundary visible.
What did not change: measurement logic, your events, or your history. Anything already marked as a conversion became a key event automatically. Nothing needed re-tagging.
The model, in one sentence
You measure important actions in GA4 as key events. When you want Google Ads to bid toward one, you import it into Ads, where it becomes a conversion.
Two products. Two counters. One underlying action.
| GA4 key event | Google Ads conversion | |
|---|---|---|
| Owned by | GA4 | Google Ads |
| Counted on | the day it happened | the day of the ad click |
| Attribution | GA4’s model, all channels | Ads’ model, ad interactions |
| Scope | every channel, including organic and direct | traffic Ads can claim |
| Used for | behaviour analysis | bid optimisation |
Why the gap is guaranteed
Different dates. This is the big one. GA4 counts a key event on the day it occurred. Google Ads credits the conversion back to the date of the click that produced it. Someone clicks an ad on Monday and buys on Friday: GA4 records it Friday, Ads records it Monday. Compare any single day and the numbers disagree, and both are right.
Different attribution. Ads credits conversions to ad interactions under its own model. GA4 distributes credit across all channels, including ones Ads cannot see. A purchase influenced by an ad, an email and an organic visit is counted differently by design.
Different scope. GA4 counts key events from every source. Google Ads only counts what it can attribute to an ad.
Different counting settings. Google Ads lets you choose between every conversion and one per click, per conversion action. GA4 has no equivalent switch.
The gap does not need reconciling. It needs assigning. Bid optimisation runs on the Google Ads number because that is what the algorithms consume. Understanding behaviour runs on GA4 because it sees channels Ads never will. Trying to make one number serve both is the actual error.
Choosing what to mark
The rename also created a chance to fix something most properties get wrong: too many key events.
Marking thirty events as key events makes none of them meaningful and, when imported, actively degrades Ads bidding by diluting the signal. A pragmatic shape:
- Key events: purchase, qualified lead, trial start, subscription. Things a stakeholder would call a business outcome.
- Not key events: scroll depth, video play, newsletter signup, PDF download. Useful, worth measuring, not outcomes.
- Imported into Ads: the smallest possible subset — ideally the one or two actions you actually want bids optimised toward.
The test: if you would not report it to someone who does not work in marketing, it is probably not a key event.
One practical trap
Marking something as a key event applies going forward only. GA4 does not retroactively reclassify historical events.
So if you mark sign_up today, last month’s sign-ups are not key events and will not appear in key event reports for that period. If you need the historical comparison, note the date you flipped the toggle and expect the series to start there.
Reading the number day to day
GA4 Simple View surfaces key events and conversion counts on the Overview tab alongside the traffic that produced them, with previous-period comparison. That is genuinely useful for the GA4 side of the question — is this trending up, and which channel moved.
What it does not do, and cannot: show you Google Ads conversions. The extension reads the GA4 Data API and Search Console, not the Google Ads API. If the number you need is the one your bidding runs on, that lives in Ads, and you should read it there rather than expecting a GA4-based tool to reproduce it.
Which is, in a roundabout way, exactly the point the rename was making.
Questions people also ask
Each answer stands on its own, so it still makes sense quoted somewhere else.
What is the difference between a key event and a conversion in GA4?
A key event is an action you have marked as important inside GA4. A conversion now refers specifically to Google Ads. The same purchase can be a key event in GA4 and a conversion in Google Ads at the same time, counted separately by two different products with different rules.
When did GA4 rename conversions to key events?
On 21 March 2024. The change was platform-wide and permanent, covering admin toggles, report columns and API fields. Events already marked as conversions carried over automatically as key events, so no re-tagging was required and historical data was unaffected.
Why do my GA4 key events not match my Google Ads conversions?
Because they are counted on different dates and credited by different attribution models. GA4 counts a key event on the day it happened. Google Ads credits a conversion back to the date of the ad click that led to it, which can be days or weeks earlier. A gap is expected, not a fault.
Did the rename change how anything is measured?
No. Only labels and some report names changed. The measurement logic, the events themselves and all historical data carried over untouched. Anything you had already marked as a conversion became a key event automatically.
How do I get a GA4 key event into Google Ads?
Mark the event as a key event in GA4, then import it in Google Ads under conversion actions from a linked Analytics property. Once imported it becomes a Google Ads conversion and is subject to Ads attribution and counting rules rather than GA4's.
Which number should I optimise campaigns against?
Google Ads conversions, because that is what the bidding algorithms actually consume. Use GA4 key events to understand on-site behaviour and cross-channel context. Optimising bids against the GA4 number means optimising against a figure the ad platform never sees.
