What is Google Analytics 4 (GA4) and what does it count?
Where GA4 sits in the ecommerce marketing technology stack is on the technologies index.
What does GA4 do?
GA4 records what people do on your site or app as events. It then groups them into reports: where visitors came from, what they did, which actions mattered to you.
A few terms you will meet straight away:
- A session is a period of user activity.
- A key event is an event you mark as important to your business.
- Engagement rate and bounce rate both describe whether sessions were engaged. Bounce rate in GA4 is not the same metric as in the older Universal Analytics.
- A conversion is the word Google Ads uses for an action it measures and bids on. Analytics and Ads use the words differently, so check which one a report means.
- UTM parameters are tags on links that tell analytics where a visit came from.
- Data-driven attribution is Google's model for sharing credit across the interactions on a path.
What do e-commerce brands use it for?
Mostly three jobs. Seeing which traffic turns into purchases. Seeing where people drop out between product page and checkout. Giving paid media a second opinion next to the ad platforms' own reports.
Funnel reports are covered in GA4 funnel exploration. Retention is covered in GA4 cohort and retention reports.
What do you have to set up yourself?
Ecommerce events such as view_item, add_to_cart and purchase are set up through the Google tag (gtag.js) or Google Tag Manager3. Google says they are not sent automatically, because they need extra context. It also notes that Shopify's pixel tracks some of them2. Check what your own shop platform sends.
Google's developer documentation puts product details in an items array, where each item needs at least an ID or a name, and says to set currency whenever you send value3. Get these wrong and the revenue in your reports is worth checking twice.
Also decide who owns the property. Administrator access should belong to you, not to an agency or a freelancer.
How do we implement it?
Set up the events
Send view_item, add_to_cart and purchase through the Google tag or Tag Manager. Include value with currency, and items with an ID or name.
Test against orders
Check that GA4's purchase count roughly matches your shop's before adding any reports on top.
Own the property
Administrator access should belong to you, not to an agency or a freelancer.
Name an owner
Someone notices when site changes break events, and knows whether a report means conversion or key event.
When should you not build on it?
Do not extend GA4 until its purchase count roughly matches your shop's. Adding reports on top of wrong data buys you wrong reports. Fix the events first.
If you want a second pair of eyes on that, our tracking audit is free. See Analytics & tracking.
What does it cost in effort?
We give no figures. The effort is in:
- Build. Deciding which events matter and sending them with the right parameters.
- Testing. Checking events against real orders.
- Upkeep. Site changes break events. Someone has to notice.
- Ownership. Access, naming and who is allowed to change settings.
Pitfalls
Assuming events arrive by themselves
Ecommerce events need setting up2.
Missing parameters
Value sent without currency, or items without an ID or name, is not what Google's documentation asks for3.
Comparing GA4 to an ad panel and expecting a match
Different tools count differently. Our article on Meta ROAS vs Shopify revenue shows why.
Mixing up conversion and key event
The words mean different things in Ads and Analytics.
Someone else owning the property
That is a risk you do not need.
Our take: Core
We rate GA4 Core. This is our view, not a market fact.
It is Google's standard analytics tool. It is event-based and documented by Google. Its limits are real, but they are known.
The limit that matters most: GA4 is not an order register. It records events your site sends, under rules it applies. Your shop platform records orders. When the two disagree, the shop is the book of record for sales.
For ZFD: We use GA4 as a second opinion, not as the answer. The first question is whether its purchase count matches your shop.
FAQ
Is GA4 the same as Universal Analytics?
No. GA4 is event-based, and some metrics, such as bounce rate, are defined differently.
Does GA4 track ecommerce purchases automatically?
Why does GA4 show different sales from my shop?
The two count different things under different rules. Treat the shop as the record of orders and GA4 as a view of behaviour.
What do I need for GA4 ecommerce reports to work?
Events with Google's recommended names, an items array with an ID or name for each product, and currency whenever you send value3.
Who should own the GA4 property?
You. Keep administrator access in your own account.
Let’s find what’s actually working.
Next step. Does your GA4 purchase count match your shop? Talk to us about your tracking setup. Or see our Analytics & tracking service.