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What is the first_visit event
October 19, 2025
- First Published: October 19, 2025
- Last Modified: October 27, 2025
If you’ve been poking around your GA4 ‘Events’ report, you’ve probably scrolled down and seen it: first__visit.
Your first thought might be, “Isn’t that just a ‘new user’?” or “How is this different from a ‘session’?”
It’s a common point of confusion and I get a lot of questions about it when my clients are taking a look in GA4.
But it’s a simple and useful event to get your head around.
It’s one of the events that Google Analytics collects automatically, and it does exactly what it says on the tin—but with one massive caveat you need to understand.
Let’s clear it up.
Table of Contents
What Is the first_visit Event?
In short, the first_visit event is an automatically collected event that fires the very first time a user visits your website (or launches your app) with GA4 enabled.
That’s it. It’s a one-time-only signal for that specific user.
Google’s official documentation confirms this. It’s designed to give you a clear marker for the moment a user is brand new to your site, according to Google’s tracking.
What Data Does It Actually Collect?
Like most GA4 events, first_visit isn’t just a simple count. It bundles up a load of useful parameters to give you context about that initial interaction. When it fires, it also collects information like:
page_location(The URL of the page they landed on)page_referrer(Where they came from)page_title(The title of the page)client_id(The anonymous identifier for the browser)session_id(The ID for that specific session)
This is part of what helps GA4 compile its broader metrics and user reports.
Unlike other events, I would suggest this should not be a key event.
How Does GA4 Know It’s a First Visit?
This is the most important bit. GA4’s entire concept of a “user” is based on browser cookies.
Imagine your browser is a visitor turning up to an office reception.
First Visit: The visitor (your browser) arrives. The receptionist (GA4) checks their list and sees they’ve never been before. They hand them a new, unique visitor ID badge (the
_gacookie) and log their arrival as afirst_visit.Return Visit: The same visitor (browser) returns a week later wearing the same ID badge (the cookie). The receptionist (GA4) scans the badge, sees they’re already in the system, and just logs a new
session_start, not afirst_visit.
If the visitor doesn’t have that Google Analytics cookie, GA4 assumes they are brand new and fires the first_visit event. It only happens once per cookie.
The Big Caveat: ‘First Visit’ Isn’t always ‘First Time’
Now, here’s the crucial part you need to remember. This event is per cookie, not per human being.
This means if a user:
Visits your site for the first time on their work laptop. (This logs one
first_visitevent).Then visits your site a few days later on their mobile phone. (This logs a second
first_visitevent).Then visits again on their personal laptop in a different browser (e.g., Firefox instead of Chrome). (This logs a third
first_visitevent).
To GA4, these look like three different “new” users, each triggering their own first_visit event, even though it’s all the same person.
The same thing happens if a user clears their browser cookies—they’ll look brand new on their next visit.
So, whilst first_visit is great for understanding new visitor traffic, always take the numbers with a small pinch of salt.
Difference between session_start and first_visit event
This is the final, and most critical, distinction.
first_visit: This event fires only once per user cookie, on their very first session.session_start: This event fires every time that user starts a new session.
A user who visits your site 10 times will have one first_visit event and ten session_start events logged against their cookie.
Think of it this way: first_visit is getting your lifetime membership card for a gym. session_start is scanning that card every time you walk through the door.
What to Do With This?
The first_visit event is a simple, automated way to flag the very first interaction a new browser cookie has with your site.
It’s the foundation for how GA4 calculates ‘New Users’ and helps you analyse the behaviour of genuine first-timers versus your returning audience.
Just remember the cookie caveat, and you’ll have a much clearer picture of what your data is really telling you.
Frequently Asked Questions (FAQs)
Is the first_visit event the same as the ‘New User’ metric in GA4?
They are very closely related. The ‘New Users’ metric you see in reports is a count of users who triggered the first_visit (or first_open for apps) event within your selected date range. So, first_visit is the event, and ‘New Users’ is the metric that counts it.
What happens if a user deletes their cookies?
If a user deletes their browser cookies and then returns to your site, Google Analytics will no longer find its cookie. It will treat them as a brand new user, assign them a new client_id, and fire a new first_visit event.
Why do I see first_visit and session_start at the same time?
You will always see a session_start event fire alongside a first_visit event. This is because the very first visit is, by definition, also the start of a new session. The key is that on all subsequent visits, you will only see session_start (but not first_visit).
Author
Hello, I'm Kyle Rushton McGregor!
I’m an experienced GA4 Specialist with a demonstrated history of working with Google Tag Manager and Looker Studio. I’m an international speaker who has trained 1000s of people on all things analytics.