Updated: October 11, 2024
Author: James Clark
If you’ve followed our guide to getting started with Google Analytics 4, you’ll know how important the concept of an ‘event’ is within this popular analytics tool. Any interaction your users have with your site or app—from a page view to a form submission—can be captured as an event. But, not all these events will be equally valuable to you or your business.
In GA4, you can choose to mark particularly important events as ‘key events.’ Then, you can use this data to further your business by understanding more about your most valuable users and how to grow that cohort.
If you’re a longstanding Google Analytics user, you may be more familiar with the term ‘goals’ (as important interactions were called in the old Universal Analytics) or ‘conversions’ (as they were called in GA4 until April 2024). The term ‘goal’ no longer exists in GA4 at all, and ‘conversion’ now has a specific meaning relating to paid advertising only. Yes, Google Analytics is always evolving!
In this article, I’ll keep to Google’s terminology and use key events to refer to any event that “contributes to the success of your business.” Only key events that are imported into Google Ads become conversions. So in GA4, every conversion is a key event but not every key event is necessarily a conversion. (To make matters more confusing, a ‘conversion’ in GA4 is called a ‘conversion action’ in Google Ads—thanks, Google.)
So if you want to understand conversions, you need to understand key events first: the typical key events for different types of site, how to set up key events in GA4, and the benefits of tracking key events. Let’s dive in.
Table of contents:
Identifying your business and website objectives
“Any event that contributes to the success of your business” is quite a broad definition, so it might be worth asking yourself:
What are your business objectives?
What would a ‘successful’ visit look like to you?
If you have an eCommerce site, you will no doubt be trying to get users to make a purchase. If you have a marketing website for your small business, you’re probably using it to generate inquiries—in which case, a user completing an inquiry form or clicking on a ‘click to call’ phone number might be successful outcomes. After all, these actions are also potential revenue generators (if only indirectly).
With editorial or publishing sites (where your revenue generally comes mainly from advertising), it can be more difficult to identify ‘success.’ Perhaps you’re trying to build an audience by encouraging email newsletter signups or site registrations—in which case, these would be good candidates as conversions.
In short, there are no hard and fast rules: the events that contribute to the success of your business will be as unique as your business itself.
Toggling events as key events
Now that you have a good grasp of the events that contribute to the success of your business, you can mark them as key events.
You can view your current conversions by going to the Key Events page in the GA4 interface (in the left-hand navigation, Admin > Data Display > Key Events). By default, if you’re using a web data stream, your Google Analytics 4 property will have only one event marked as a key event: the purchase event. This event indicates that an eCommerce transaction has occurred, and is always counted as a conversion.
To mark an event as a key event, go to the Events page (Admin > Data Display > Events). This lists all the existing events being collected on your site, and shows how many of each have occurred within a given timeframe. If you’ve turned on GA4’s enhanced measurement feature (and we strongly recommend you do), you may have received some automatically tracked events, including:
file_download — When a user clicks a link leading to a file
click — When a user clicks a link to an external site
view_search_results — When a user conducts a site search on your website
scroll — The first time a user reaches the bottom of each page
In addition to these events, you may see other events that your platform or CMS is sending. For example, Wix’s ‘live chat’ widget sends events, including ‘Chat - Opened’ and ‘generate_lead’ (when an inquiry is submitted). Third-party plugins and add-ons may also send events. Using a platform that automatically sends events is particularly useful for eCommerce, which can be complicated to set up manually.
To mark one of your events as a key event, simply click on the corresponding toggle on the right-hand side (as shown above). Now, when you go back to the Key Event page, your new conversion will be listed there. This approach only works if the event has been collected at least once in the timeframe you are looking at—otherwise you won’t see it listed.
Note: You can also untoggle an event at any time—except the purchase event, that is.
Creating custom events to use as key events
What happens if you only want specific instances of an event to be counted as a key event?
Let’s say you’re raising money for charity and you’ve built a website to help create awareness. Your site has links to lots of other websites, including one to the fundraising platform where people can make a donation.
You’re already automatically tracking clicks on all these links as outbound ‘click’ events through GA4’s enhanced measurement feature. You’ve also thought about the aims of your website, and you’ve identified that clicks on the fundraising link would make an ideal key event.
But, if you go ahead and toggle the ‘click’ event as a key event, that will mark all link click events as key events, which is not what you want. Instead, you will need to create a new, more specific, custom event based on the existing ‘click’ event, then mark this new event as a key event.
Here’s how:
01. In Admin > Data Display > Events, click on Create Event.
02. Click Create.
03. Give your event a name. There’s a limit of 40 characters, you can’t use spaces, and event names in GA4 are normally lowercase. Google’s enhanced measurement events tend to follow the pattern action_object, so something like “fundraising_click” would be perfect.
04. Next, add some ‘conditions.’ When all of these conditions are met at the same time, your new event will trigger. The first condition is simply “event_name equals click.”
05. Click Add condition. This second condition is where you’ll indicate that the event should only trigger on clicks specifically to the fundraising platform. For that, we need the parameter “link_url equals” and then the full URL (as shown below).
06. Click Create in the top-right.
Finally, close the Create events panel. Next, you’re ready to mark the custom event you just created as a key event.
Marking custom events as key events
You’re now back on the Events page, but don’t worry that you can’t see your new event. It might take 24 hours or so for it to appear here after someone has performed the action on your site—which means you won’t be able to toggle it as a conversion yet.
Fortunately, there’s another way to set up the key event, and we can do it straight away:
01. Go to Settings > Data Display > Key Events.
02. Click New key event.
03. Enter the name of the custom event you saved earlier (in our example, “fundraising_click”) in the New event name box and click Save.
The reason I don’t recommend this approach for setting up all your key events is that it introduces the risk of getting the event name wrong. It’s easy to misremember your form submission event name as form_submission instead of form_submit, for example. Generally, it’s safer to use the toggles on the Events page.
Finding and using event parameters
In our fundraising example, you’ll notice we used an event parameter called “link_url.” An event parameter is just an additional piece of information about that event. So, ‘click’ events have parameters including:
link_url — The full URL you are linking to (e.g., https://fundraiser.co.uk/example)
link_domain — The domain you are linking to (e.g., fundraiser.co.uk)
outbound — Here, a value of ‘true’ indicates that it is a click to an external website.
But, how do you find out what parameters are available for you to use when you’re setting up a custom event?
You could check Google’s documentation, at least for the enhanced measurement events (such as ‘click’). But, the simplest and surest way is to go to Reports > Realtime and look at the Event count by Event name card. This lists all the events that have happened on your site or app in the past 30 minutes:
Click on any event to see its parameters, then click on any parameter to see the values belonging to that parameter.
So, by going to your website and triggering the event you want to use as a key event, you will be able to check the parameters and values in the Realtime report before setting everything up.
A more advanced approach would be to use GA4’s built-in debug mode and DebugView report. This lets you see only the events you are triggering, rather than every event being triggered by every visitor to your site. So, if your site receives a lot of traffic, this approach makes it much easier to find the events and parameters you are looking for.
Key event limits in GA4
A standard GA4 property can have up to 30 different key events.
This may sound like a lot, but given that you can have as many events as you like in your web data stream, it’s a definite limitation—and something to bear in mind when you start identifying the events that contribute to the success of your business. Enterprise customers paying for Google Analytics 360 have a higher limit of up to 50 conversions.
And, here’s a different kind of limitation: Marking an event as a key event doesn't affect data you've already collected, only new data from that point on. So, it’s important to identify your key events as early as you can so as to make full use of the data you gather about your users’ behavior.
Using key events in reports
Now that you’ve set up key events, you can make use of this data in GA4 reports. The place to start is Reports > Engagement > Pages and Screens. This shows you a list of pages on your site along with the number of views, events, and key events that have taken place on each. The top row gives you a total for all pages.
OK, but say you are tracking two key events, a ‘click to call’ event (which is somewhat valuable to your business) and a purchase (which is highly valuable). A total that includes both isn’t necessarily that insightful. Fortunately, there are two ways you can drill down further into the data to understand the exact value being created.
First, use the filter on the ‘key events’ column to select a specific key event:
Second, you will also see a column called “Total revenue.” If you’re tracking an eCommerce site, your ‘purchase’ events will have a ‘value’ parameter capturing the monetary value of the purchase. This allows your Pages and Screens report, as well as other reports in GA4, to show how much revenue your site is generating. Here it is in the Events report:
It’s possible for other conversions to be assigned a value, too. Let’s say you run a plumbing business and you know that a new customer is, on average, worth $500 to you. You also know that one in five of your contact form submissions converts into a paying customer. So, it would be reasonable to give a contact form submission a nominal value of $100 (that is, $500 divided by five).
Loves Data has a useful guide to adding a monetary value to key events (here called “conversions”).
Istarted this article by saying that key events are events that “contribute to the success of your business.” One of the biggest benefits of tracking key events is that you can see how marketing activity is contributing to the success of your business.
The place to go for this information in GA4 is the Advertising section. Don’t be fooled by the name: it gives you insight not just on paid advertising (such as search and display ads), but on all of your traffic sources, including organic search.
When you first try to access Advertising, Google Analytics will prompt you to link your GA4 property to a Google Ads account (if you haven’t done so already). You don’t need to actually run any ads to see these reports (i.e., it won’t cost you any money), but you do need a connected Ads account:
This section provides information on both key events and conversions (that is, key events you’ve imported into Google Ads). Individual reports and cards will either focus on one or the other, so check the card titles to understand what they are showing you.
Let’s look at the Advertising Snapshot first (Advertising > Advertising Snapshot). The card in the middle shows you your traffic ‘channels’ and how many key events each channel has generated:
There’s an easy-to-miss dropdown in the top-left of this overview report that lets you select and deselect individual key events. So, you may find that one traffic source is responsible for most of your email newsletter signups, but another traffic source (perhaps email) is responsible for purchases.
However, user journeys are becoming more complex and a user may come to your site several times before they convert. The Attribution Paths report (Advertising > Attribution > Attribution Paths) illustrates this.
The top of the report shows your most common “early,” “mid,” and “late,” touchpoints to give an overview of your converting users’ behavior:
Underneath this are the specific conversion paths that users take. In the screengrab below, you can see that users to this particular site often make two, three, or four visits via organic search before performing a key event:
Choosing an attribution model
What happens if a user comes to your website via lots of different channels before converting? Perhaps their first visit is via one of your paid search ads. Later, they come back via organic search. They visit again via a link in an email newsletter—and then finally convert.
Which touchpoint (or touchpoints) should get the credit for the conversion?
This is where attribution models come in: An attribution model is simply a set of rules that decides how credit is allocated. Credit here means both the number of key events and any revenue coming from those events.
GA4 makes it very straightforward to see the impact of its two attribution models via the Attribution Models report (Advertising > Attribution > Attribution Models). The report shows you key event numbers and revenue for each of your traffic channels—and how those numbers would look under either the ‘data-driven’ or the ‘last-click’ model:
‘Last click’ is the easier one to understand: it attributes all credit to the final touchpoint. This model was the default in the old Universal Analytics, so opt for this if you want to remain consistent with your historic data.
Within last click, you can choose either ‘paid and organic channels’ or ‘Google paid channels.’ The Google paid channels option always gives credit to the final Google Ads touchpoint (if there was one), ignoring any later clicks from organic channels. This model is useful for analyzing the effectiveness of paid campaigns.
If you’re running paid ads for a client, you may be tempted to choose this model just to make your results look better—please try to avoid that temptation as it could lead to difficulty down the line when the client asks why organic or social aren’t driving much revenue.
‘Data-driven’ is GA4’s default model. Instead of following a fixed set of rules, it looks at your historical data and uses machine learning to work out how to assign credit. It’s a powerful feature, but something of a black box in that you can’t see exactly how it works. As Google says, “each Data-driven model is specific to each advertiser and each key event.”
All of GA4’s other attribution models (first click, linear, time decay, and position-based) were deprecated in November 2023.
Your choice of model is more than just an interesting exercise. If you’re using your conversion data to make business decisions (for example, on where best to spend your marketing budget), then choosing the most appropriate model can help with that. It’s worth considering: do you want to focus on the ‘converting’ channel only, or consider all the channels that might have contributed to that conversion?
In the non e-Commerce example below, moving from ‘last click’ to ‘data-driven’ massively increases the number of key events shown as being driven by organic social. This tells us that organic social is important earlier in the user journey—perhaps how users first learn about the brand:
Although the Attribution Models report lets you see the impact of different models, you’ll find the setting to actually change your chosen model in Admin > Data Display > Attribution Settings.
Advanced uses for key events and conversions in GA4
Now, you have seen how to set up key events and conversions and make use of this data in GA4’s predefined reports. But, there are many other applications—let’s take a quick look at some of them.
Explorations
If you prefer to build your own reports (or ‘Explorations’ as GA4 calls them), then you can add key event-related metrics and dimensions to any of those reports.
In July 2022, Google added conversion rate metrics: a popular and much-requested feature from Universal Analytics. Originally called ‘user conversion rate’ and ‘session conversion rate,’ these metrics have since been renamed to ‘user key event rate’ and ‘session key event rate’ to make it clear that they don’t just apply to Ads conversions.
User key event rate: The percentage of users who have performed a key event.
Session key event rate: The percentage of sessions in which a key event was performed.
Analytics Mania has a comprehensive guide to finding and using these key event rate metrics.
Google Ads
We’ve already seen that to enable the Advertising reports in GA4, you need to link your GA4 property to your Google Ads account. You can then import your key events into Google Ads, where they become conversions (in GA4) and conversion actions (in Google Ads). You can use this data to optimize your bids so your campaigns generate more conversions for less ad spend.
Importing your GA4 key events isn’t the only way to send conversion data to Google Ads. You could, for example, use a Google Ads conversion tag in Google Tag Manager and bypass GA4 completely. However, linking GA4 with Google Ads and importing key events gives you the benefit of seeing the same data in both locations.
To start the process, go to Goals > Summary in Google Ads and click Create Conversion Action. Then choose the Import option from the following selection:
For more on linking Google Ads and GA4, take a look at the Optimize Smart guide.
Audiences
Another section of GA4 that makes use of conversion data is Audiences (Admin > Data Display > Audiences). Here, you can build a segment of users who meet certain conditions that are important to your business (e.g., users who have made a purchase, users who have performed any key event, etc).
GA4 also offers so-called ‘predictive audiences’: one of the presets here is “users who are likely to make a purchase in the next seven days.” However, you will only be eligible to use these if your site meets certain criteria, one of which being a minimum traffic threshold.
These audiences have several applications: first, you can add them as a ‘comparison’ to your standard GA4 reports and see what makes them different to your overall users. Perhaps they are more likely to come from a particular country, or visit a certain section of your site. This could be valuable marketing intel.
If you’ve linked GA4 with Google Ads, your audiences are also available for use there. This allows you to target your paying customers (or valuable users) with relevant messages as part of so-called ‘remarketing’ campaigns.
The Google Analytics help article on audiences is a good place to start if you are interested in exploring these possibilities.
Key event tracking helps you get the most from your site traffic
We started this guide by saying that key events are events that contribute to the success of your business. Tracking key events (and conversions) also contributes to the success of your business—by helping you to understand your audience, report on revenue, target your marketing, and make smarter decisions about your website.
Not everyone sees the benefits of setting up key event tracking... but, hopefully, I’ve shown you that it’s the key to unlocking the full value of website analytics for your business.
James Clark is a web analyst from London, with a background in the publishing sector. When he isn't helping businesses with their analytics, he's usually writing how-to guides over on his website Technically Product. Twitter | Linkedin