How to Find Traffic Source in Google Analytics 4

Knowing where your website visitors come from tells you exactly which of your marketing efforts are hitting the mark. This isn't just about spotting traffic spikes, it's about understanding which channels deliver valuable users who actually engage and convert. This guide will walk you through exactly how to find and analyze your traffic source data directly within Google Analytics 4.

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First, Understand GA4's Traffic Dimensions

Before jumping into the reports, it’s helpful to know what you’re looking for. In Google Analytics 4, traffic data is categorized using specific "dimensions." Think of dimensions as the different labels GA4 uses to describe your traffic. The most important ones for source analysis are:

• Session source / medium: This is your go-to dimension. It tells you where the user’s most recent session came from. For example, if a user clicked a link in your email newsletter to visit your site today, their session source/medium would be something like "newsletter / email."
• First user source / medium: This dimension looks back in time to tell you where a user first came from when they initially discovered your site. If that same user from the example above first found you through a Google search two months ago, their first user source/medium would remain "google / organic."

Why the difference? Session source helps you measure the effectiveness of specific, recent campaigns (e.g., "Did my blog post promotion on Facebook yesterday drive traffic?"). First user source helps you understand which channels are best at acquiring new customers over the long term, regardless of how they returned later.

You may also see these dimensions broken out individually:

• Source: The specific origin of your traffic (e.g., google, facebook.com, hubspot).
• Medium: The general category of the source (e.g., organic, cpc, email, referral).
• Campaign: The name of a specific marketing campaign, which you typically set yourself using UTM parameters (e.g., summer-sale-2024).

The Quickest Way: The Traffic Acquisition Report

For a fast, clear overview of where your traffic is coming from, GA4’s built-in Traffic Acquisition report is the best place to start. It organizes your data based on the session source, making it perfect for analyzing recent performance.

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How to Access the Report:

1. Log in to your Google Analytics 4 property.
2. On the left-hand navigation menu, click on Reports.
3. Under the "Lifecycle" collection, click on Acquisition.
4. From the dropdown, select the Traffic acquisition report.

You'll now see a table showing various channels, ranked by the number of users they drove during your selected date range. By default, GA4 groups your traffic into broad "Session default channel groupings" like Organic Search, Direct, Paid Search, and Referral. This is great for a high-level view.

Getting More Granular Details

To see the specific sources and mediums, you need to change the primary dimension of the report. This is easy to do.

1. In the Traffic acquisition report, locate the table of data.
2. Click the small downward-facing arrow next to the current primary dimension (which is likely "Session default channel group").
3. From the dropdown list that appears, select Session source / medium.

Voilà! The table will instantly update, showing you the exact combinations of where your traffic came from, such as "google / organic," "linkedin.com / referral," or "google / cpc." This is the view most digital marketers and business owners use daily to monitor which platforms are performing best.

Connecting Traffic Sources to Results

Just knowing a channel sends traffic is only half the story. The real question is: does that traffic lead to meaningful action? You can answer this by looking at engagement and conversion metrics right within the same report.

Scroll the report table to the right, and you’ll see columns for:

• Engaged sessions: The number of sessions that lasted longer than 10 seconds, had a conversion event, or had at least 2 page views. This is a far better measurement of quality than the old "Bounce Rate."
• Engagement rate: The percentage of sessions that were engaged. A higher rate suggests the traffic from that source is relevant and interested.
• Conversions: This is the most important column. It shows you the total number of conversion events (like a purchase, form submission, or sign-up) attributed to each traffic source.

By sorting the table by conversions, you can quickly identify which traffic sources aren’t just sending visitors, but sending visitors who become customers or valuable leads.

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Filtering the Report for Deeper Insights

What if you only want to see traffic from a specific country or from mobile devices? You can easily filter the report to narrow down your analysis.

1. At the top of the report page, click the Add filter button.
2. A panel will open on the right. Search for and select the dimension you want to filter by - for instance, "Country."
3. Select the match type (e.g., "exactly matches") and choose the value (e.g., "United States").
4. Click the blue Apply button.

Your report will now only show data for traffic originating from the United States, allowing you to compare channel performance within that specific market.

Using Secondary Dimensions to Add Context

Secondary dimensions allow you to cross-reference your traffic sources with another piece of data, giving you more context. This is where you can start uncovering some powerful insights.

For example, you could add "Landing page" as a secondary dimension to see which specific pages are attracting the most traffic from your top channels.

How to Add a Secondary Dimension:

1. In the same report table, click the blue "+" icon next to the primary dimension header.
2. A search box will appear. Search for the dimension you want to add, such as "Landing page + query string" or "Device category."
3. Select it from the list.

The table will reload with an additional column. Now you can see not only that Google organic search sent you 1,000 users, but that 600 of them landed on your new blog post while 400 landed on your homepage - and you can compare the conversion rates of each!

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Don't Forget About UTM Parameters

To get the most accurate and detailed traffic source data, you must use UTM parameters. These are small snippets of text you add to the end of a URL to tell Google Analytics exactly where a user came from and which campaign they clicked on.

For example, instead of just linking to your site from an email newsletter with yourwebsite.com, you'd use a link like this:

yourwebsite.com?utm_source=spring-promo&utm_medium=email&utm_campaign=25-off-sale

When someone clicks that link, GA4 will know to categorize their traffic under:

• Source: spring-promo
• Medium: email
• Campaign: 25-off-sale

Without this, that valuable traffic from your email campaign might be incorrectly labeled as "Direct" traffic, leaving you blind to its true performance. Consistently using UTMs across your emails, social media posts, and ad campaigns is one of the most important habits for data-driven marketers.

Final Thoughts

Mastering traffic source analysis in Google Analytics 4 allows you to move beyond simply counting visitors and start understanding marketing performance in a meaningful way. By regularly checking the Traffic Acquisition report and applying dimensions and filters, you can confidently decide where to invest your time and budget for the best results.

While GA4 is excellent at showing you what's happening on your website, performance analysis becomes complicated once you need to connect that data to other platforms, like your ad spend from Facebook Ads or your final sales numbers in Shopify. So much of our time is lost just trying to stitch those different reports together. Our goal with Graphed is to eliminate that manual work. We centralize all your data so you can just ask a question in plain English - like "show me which Shopify products were driven by Google organic traffic last month" - and get an answer with a live, updating dashboard in seconds, not hours.