Key takeaways
- GA4 renamed conversions to key events in 2024. What changed, how to pick the key events that signal real leads, and how to mark them for Google Ads.
- In GA4, a key event is any action you have flagged as important. A 'conversion' now means the Google Ads metric you can bid towards, and the two are not the same.
- Marking a key event in GA4 changes your reports only. It does nothing in Google Ads until you create a conversion from that key event and import it.
- Choose a short list of key events that represent real enquiries or sales, not micro-actions like page views, so your reporting and bidding stay honest.
- Set the UK time zone and GBP currency, confirm the Google tag fires, then mark your key events and import the ones that matter into Google Ads.
In GA4, “key events” are what used to be called “conversions”, and “conversions” now means the separate metric you see in Google Ads. Google made the switch in 2024 to stop two different numbers sharing one name. This guide explains what moved, why it matters for a UK business, and how to choose the key events that stand for real leads, then mark them for Google Ads.
What changed, in one line
In 2024 Google renamed GA4 “conversions” to “key events”, and kept the word “conversions” for the Google Ads metric you bid towards.
Nothing broke in the move. The measurement logic stayed the same, your historical data stayed intact, and any conversion events you had already configured were carried over automatically as key events. The only real change was the wording and the report labels.
The reason was confusion. GA4 and Google Ads both used “conversions” for numbers that were counted in different ways, so the same word meant two different things on two different screens, and teams kept comparing figures that were never meant to match. Splitting the terms makes it clear which system you are looking at. Google sets out the distinction in full in its own documentation (Google Analytics Help, Conversions vs. key events in Google Analytics).
Key events vs conversions: the difference that matters
A key event lives in Google Analytics and shapes your reports. A conversion lives in Google Ads and can be bid towards. They are related, but they are not the same thing.
The hierarchy is worth holding in your head: every interaction is an event, an event you flag as important becomes a key event, and a key event you share with Google Ads becomes a conversion there. Each step is a deliberate choice, not an automatic promotion.
Here is how the two compare side by side.
| GA4 key event | Google Ads conversion | |
|---|---|---|
| Where it lives | Google Analytics | Google Ads |
| What it is for | Flagging an action as important in your reports | An action Smart Bidding can optimise towards |
| How it is created | Mark an existing event as a key event | Create a conversion from a key event, or use a native Ads tag |
| When it is counted | When the action happens, on GA4’s attribution | By the date of the ad click, inside a conversion window |
| Affects your ad spend | No, on its own | Yes |
Why the rename matters for your reporting
Because the two systems count differently, GA4 and Google Ads will rarely show identical totals, and that gap is expected rather than a fault.
GA4 records a key event when it happens and attributes it with its own model. Google Ads counts a conversion against the date of the ad click, inside the conversion window you set, and adds modelled conversions for the journeys cookies no longer capture. Different attribution, different time windows, different rules, so the numbers drift apart. A difference of twenty to thirty per cent between the two is common, and it does not mean either one is wrong.
What helps is knowing which number answers which question. Use GA4 key events to understand on-site behaviour and which pages and channels bring enquiries. Use Google Ads conversions to judge and steer campaign performance. If you want that whole picture wired up properly, it is the core of our analytics and measurement work.
How to choose the key events that represent real leads
Pick a short list of actions that mean money or a genuine enquiry, and leave everything else as an ordinary event.
For most UK small businesses, the key events that matter are the handful a salesperson would recognise as a lead or a sale:
- A submitted enquiry or contact form
- A click to call on a mobile
- A booking, quote request or demo request
- A completed purchase or checkout
- A newsletter or account sign-up, if that genuinely feeds sales
Resist the urge to mark page views, scrolls or every button click as key events. They are useful as ordinary events for context, but as key events they flood your reports with noise and, once imported, push Smart Bidding towards cheap actions instead of real customers. A good rule is one or two primary key events that you bid towards, plus a small number of secondary ones you watch but do not optimise hard for.
Map your events before you mark them
List the actions that matter, confirm each one is already being collected as an event, then decide which deserve key-event status.
Some events arrive for free through Enhanced Measurement, such as outbound clicks and form interactions. Others you send deliberately through Google Tag Manager, for example a generate_lead event on a submitted contact form. Open Admin, then Events, and check the action is showing up before you rely on it. If an event is not being collected, marking it as a key event will measure nothing.
How to mark a key event in GA4
In Admin, open Events, find the event you care about, and toggle “Mark as key event”.
- Make sure your GA4 property is set to the United Kingdom time zone and British Pound currency, so days and revenue line up with your trading rather than California’s.
- Confirm the Google tag is firing on every page.
- In Admin, open Events (newer properties show a Key events screen), find the event, and switch on Mark as key event.
- Repeat for each action on your shortlist, and no more.
That is all it takes inside GA4, and it is worth being clear about what it does: marking a key event changes your GA4 reports only. Any event you collect can be promoted this way (Google Analytics Help, Key events). For the full property build, from creating the data stream to filtering internal traffic and wiring in consent, follow our GA4 setup guide for UK websites.
How to turn a key event into a Google Ads conversion
A key event does nothing for your campaigns until you create a Google Ads conversion from it and import it, so this is the step that actually connects data to spend.
With your GA4 property and Google Ads account linked, you create the conversion from the key event rather than building it again by hand:
- Link the GA4 property to your Google Ads account in Admin, under Product links.
- In GA4, go to Advertising, then Conversion management, and choose to create a new conversion.
- Select your Google Ads account and the key events you want to bring across as conversions.
- Review and save, then check the conversion appears in Google Ads.
Once imported, the data is shared between the two platforms so you are looking at the same action in both (Google Ads Help, Create Google Ads conversions based on Google Analytics key events). Import only the key events you actually want to bid towards. For the native-tag-versus-import decision, Enhanced Conversions and the UK consent rules that sit around all of this, work through our Google Ads conversion tracking setup.
Common mistakes we see
Most key-event problems come down to the same few habits, and all of them are easy to avoid once the terms are clear.
- Marking everything as a key event. A long list buries the two or three that matter and distorts bidding.
- Assuming a GA4 key event is already a Google Ads conversion. It is not until you import it, so campaigns optimise towards nothing.
- Counting one action through both routes. A native Ads tag and a GA4 import for the same action double the number. Pick one source per action.
- Expecting the two numbers to match. Different attribution and windows mean they will not, and chasing a perfect match wastes hours.
- Bidding towards micro-actions. Page views and clicks are signals, not outcomes. Keep them as ordinary events.
Get your measurement set up right
Set the terms straight, mark a tight set of key events, and import only the ones worth bidding on, and the rest of your reporting gets easier to trust.
Key events tell you what is happening on your site. Google Ads conversions tell you what your spend is doing. Keeping the two clear, and connected, is what turns analytics into decisions instead of guesswork.
If you would rather have a UK team set it up and sanity-check it, book a free growth review and we will look at how your key events and conversions are configured, or get in touch and tell us what you are trying to measure.