How to Build a Funnel Exploration in GA4
Funnel reports answer where people quit, if you build them correctly. Here is how, and the settings that change the numbers.
Funnel explorations answer the most useful question in analytics: where exactly are people giving up?
They also produce completely different numbers depending on three settings most people never touch, which is why two people can build the same funnel and disagree about the results.
Here is how to build one that tells you the truth.
Before you build anything
A funnel is only as good as the events underneath it. If your add to cart event fires on button click rather than on successful add, your funnel will show a drop off that is actually just out of stock variants.
So check your events first. Walk through the journey yourself in GTM preview and confirm each step fires once, at the right moment, with the right values.
Building the funnel
Explore, then Funnel exploration. You get a blank funnel with some default steps, which you should delete.
Add your steps in order. Each step is a condition, usually an event name, sometimes an event with a parameter condition, sometimes a page view on a specific path.
A standard ecommerce funnel:
session_start or view_item, depending on whether you want everyone or only product viewers
add_to_cart
begin_checkout
add_payment_info
purchase
A lead generation funnel:
Landing page view
Form start, if you track it
Form submit
Qualified lead, if you push that back from your CRM
That second funnel is where the interesting drop off usually lives, and most sites cannot build it because they never track form start. It is worth adding: multi step form tracking.
The three settings that change your numbers
Open versus closed funnel
A closed funnel only counts users who entered at step one. An open funnel lets people join at any step.
Default is closed. Use closed when you want to understand a specific journey. Use open when people legitimately arrive mid funnel, for example landing directly on a product page from a shopping ad.
Switching between them can change your conversion rate dramatically, and neither number is wrong. They answer different questions.
Trended versus standard
Standard shows the funnel as a bar chart at one point in time. Trended shows each step’s completion rate over time.
Trended is underrated. It is how you spot that checkout completion dropped on the eleventh, which is the day of the release.
Make it a segment
Right click any step and you can build a segment from the users who dropped off there. Then use that segment in other explorations to work out who they were.
This is the most useful feature in the tool and almost nobody knows it is there.
Adding a breakdown
Drag a dimension into the breakdown field and the funnel splits by it.
The ones worth trying:
Device category. Mobile checkout drop off is usually worse and usually fixable.
Session default channel group. Different traffic sources have genuinely different funnels.
Landing page. Sometimes one page is quietly broken.
Browser. Occasionally reveals a real bug affecting one browser only.
Limit yourself to five or so breakdown values or the chart becomes unreadable.
Reading it without fooling yourself
Three traps.
First, a big drop between steps is not automatically a problem. The drop from product view to add to cart is supposed to be large. Compare against your own history, not against an imaginary standard.
Second, funnel steps do not have to be sequential in time unless you tick the option to make them. By default, a user who did step three before step two can still count. Turn on the next step within setting if order matters.
Third, GA4 funnels are user based, not session based, by default. Someone who browses today and buys next week counts as a completion. That is often what you want, but know that it is happening.
What to do with what you find
A funnel tells you where, never why. The where is the easy part.
So pair it with something that shows you the why. Session recordings filtered to the drop off point. A survey on the page. Or simply doing the journey yourself on a mid range Android phone on a slow connection, which is a genuinely revealing exercise.
A funnel worth building today
If you build one thing, build a trended funnel of your main conversion path, broken down by device, covering the last ninety days.
Then look for the day something changed. There usually is one, and it is usually a release nobody connected to the drop.
Need this built properly?
Funnels turn a vague sense that something is wrong into a specific step you can fix. I set up and repair tracking for ecommerce stores and lead generation businesses, so the numbers in your ad accounts match the money in your bank account.
Have a look at what I do, or book a call and we can go through your setup together.
