What Does First User Mean in Google Analytics 4?

If you’ve spent any time in Google Analytics 4, you’ve probably noticed a family of dimensions that all start a little strangely: "First user..." What is a "First user default channel group," and how is it different from the standard "Session default channel group"? This article clears up the confusion, explaining exactly what these user-scoped metrics mean, why they are so valuable for understanding customer acquisition, and how to use them to find your most effective marketing channels.

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User vs. Session: The Big Shift in GA4

To understand what "first user" means, you first need to grasp the fundamental difference between how Universal Analytics (the old version) and Google Analytics 4 think about your data. The old model was primarily built around sessions, which are groups of user interactions within a specific timeframe.

GA4, however, adopts a more flexible, user-centric model built around events. This allows it to look at your data from different perspectives, or "scopes." The two most important scopes for this conversation are:

• User Scope: This looks at the entire lifetime of a user, starting from their very first visit to your website or app. It answers the question: "Who is this person and how did we first meet them?"
• Session Scope: This looks at a single visit or session. It answers the question: "How did this user get to our site for this specific visit?"

Think of it like this: a new customer might first learn about your clothing brand from an Instagram ad. Six months later, they could remember your brand, search for it on Google, and make a purchase.

• The user-scoped data would attribute this customer to Instagram forever. Instagram is how you acquired them.
• The session-scoped data for their purchase visit would attribute that specific session to Google Organic search. Google is how they got to you that day.

Any dimension that starts with "First user" is operating on the user scope. It tells you about the origin story of that user, completely ignoring how they came to your site in subsequent sessions.

Breaking Down the "First User" Dimensions

While GA4 offers several "First user" dimensions, a few are more critical to reporting than others. Let’s break down the most common ones you'll encounter and what they tell you.

First User Source / Medium

This is arguably the most important user-scoped dimension. It tells you the specific source (the "where," like google or facebook.com) and medium (the "how," like organic or cpc) responsible for acquiring a user during their very first session.

Example: A user clicks on a sponsored link in a Google search for "best running shoes." They land on your site for the first time.

• Their First user source / medium is permanently set to google / cpc.
• A week later, they type your website URL directly into their browser. The Session source / medium for that visit is (direct) / (none).
• Despite the direct visit, their First user source / medium remains google / cpc. This tells you that the paid search ad was what originally brought this person into your marketing funnel.

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First User Campaign

As you can guess, this dimension locks in the name of the marketing campaign that brought a user to you for their first visit. It’s tied to the UTM parameters you use in your marketing URLs (specifically utm_campaign).

Example: You run a Valentine's Day campaign on Facebook with a unique utm_campaign tag, feb_14_promo.

• A user clicks on an ad from this campaign and visits your site for the first time. Their First user campaign is set to feb_14_promo.
• In May, they click a different ad from your summer_sale campaign. The Session campaign for this session will be summer_sale.
• However, their First user campaign attribute will always be feb_14_promo, helping you measure the true acquisition power of your Valentine's Day push.

First User Default Channel Group

This provides a broader, more high-level view of a user's origin. It’s GA4’s rule-based grouping of common traffic sources, such as 'Paid Search,' 'Organic Search,' 'Direct,' and 'Paid Social.' This dimension records which of these channels a user came from on their initial visit.

Example: Someone finds your blog for the first time through a search engine.

• Their First user default channel group is tagged as 'Organic Search.'
• Later, they subscribe to your newsletter. When they click a link in an email, the Session default channel group for that visit is 'Email.'
• When you analyze your reports, this user is always counted as having been acquired by the 'Organic Search' channel, allowing you to trace the long-term value generated by your content marketing and SEO efforts.

Why "First User" Metrics are Mission-Critical for Marketers

Now that you know what these dimensions are, why should you care? Separating the 'first touch' from subsequent touches allows you to measure your marketing in a much more sophisticated way.

1. Identify Your True User Acquisition Engines

Many marketing channels are great at re-engaging existing users but poor at attracting new ones. For example, your branded search campaigns (people searching for your company name) likely have high conversion rates, but they’re mostly attracting people who already know you.

By focusing on First user dimensions, you can answer the crucial question: "Which channels are actually bringing a new audience into my funnel?"

You may discover that while your retargeting ads drive a lot of conversions (from a session perspective), your content marketing or affiliate program is the source of 90% of your new customers. This insight tells you where to invest your budget for top-of-funnel growth, not just bottom-of-funnel conversions.

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2. Understand the Long-Term Value of Your Channels

Last-click attribution is misleading. A user might be introduced to your brand via a high-effort YouTube tutorial, forget about you, then see a simple display ad a month later, click, and convert. A session-scoped report might give all the credit to the display ad, overlooking the powerful educational content that started the relationship.

Using First user source / medium allows you to track customer lifetime value (LTV) back to the original acquisition channel. You can build reports that answer questions like:

• Do users acquired through Organic Search spend more over their lifetime than those acquired through Paid Social?
• Which of my cold-outreach campaigns generated the highest LTV customers a year later?
• Is the high cost-per-acquisition on that B2B podcast sponsorship justified by the long-term value of the customers it generates?

This shifts the conversation from "what made them convert today?" to "what makes our best customers find us in the first place?"

3. Properly Evaluate Top-of-Funnel and Brand Awareness Campaigns

The impact of top-of-funnel marketing is notoriously difficult to measure with session-based reporting. A LinkedIn article, an influencer mention, or a viral TikTok video might introduce thousands of new people to your brand without driving immediate conversions. These users might come back weeks later through a different channel to finally buy.

First user dimensions are perfectly suited for measuring the impact of these efforts. By filtering your reports for the campaign or channel in question, you can see how many new users it brought to your ecosystem. You can then track what those users did in the following weeks and months, justifying the investment in building awareness rather than only chasing last-click sales.

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How to Access and Use "First User" Data in GA4

Google Analytics 4 has two dedicated reports in the Acquisition section that neatly separate user and session scope.

Here’s how to find and use them:

1. From your GA4 property, navigate to the sidebar menu and click on Reports.
2. Under the Life cycle collection, expand the Acquisition topic.
3. Here, you will see two key reports: User acquisition and Traffic acquisition.

User acquisition: First user... Report

Think of this as your "origin story" report. By default, its primary dimensions are all user-scoped: First user default channel group, First user source / medium, etc. This report is exclusively dedicated to telling you where your new users came from. It is the best place to get a high-level view of which channels are most effective for acquiring a genuinely new audience.

Traffic acquisition: Session... Report

This is the classic traffic report most marketers are used to. All its default primary dimensions are session-scoped (Session default channel group, Session source / medium, etc.). This report tells you how users arrived at your site for each individual session, regardless of whether it was their first visit or their hundredth. Use this to analyze session-specific performance, like which campaign drove the most sessions or conversions yesterday.

The single best way to cement your understanding is to open these two reports in side-by-side tabs and compare the data. You’ll immediately see how the story they tell is different but equally valuable.

Customizing a Report to Combine Scopes

The real power comes from combining these views. For instance, you might want to look at a standard Monetization report but see the original acquisition channel for the users who are purchasing.

• Go to any standard report, like Tech details under the User attributes section.
• At the top of the data table, click the small blue '+' icon to add a secondary dimension.
• In the search box, type "First user" and select First user source / medium.

Instantly, you can now see the First user source / medium alongside the Device Category, answering a question like, "Are the new users we acquire through Facebook Ads more likely to be mobile or desktop users?"

Final Thoughts

Distinguishing between the 'user' and 'session' scope is one of the most important concepts to master in Google Analytics 4. The "First user" dimensions provide a powerful lens to view your marketing performance, helping you look beyond single-session metrics to understand the true origin story of your customers and their long-term value.

Connecting all your conversion data across different platforms - be it ads from Facebook, search campaigns from Google, or sales data from Shopify - can be a huge manual effort. At Graphed we remove that friction by connecting all your data sources automatically. Instead of wrestling with GA4 reports, you can simply ask in plain English, "Show me a comparison of customer lifetime value by first user source," and get an instant, real-time dashboard that answers your most important acquisition questions.