What is Affiliates in Google Analytics?

If you've ever looked at your traffic sources in Google Analytics 4, you might have seen a channel simply labeled "Affiliates." This can be a bit confusing, as it often shows very little data or mixes in with the more familiar "Referral" traffic. This article will show you what the Affiliates channel in GA4 is, how Google identifies this traffic, and how you can use this data to properly track and grow your affiliate marketing program.

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What Exactly is the "Affiliates" Channel in GA4?

In Google Analytics 4, "Affiliates" is one of the Default Channel Groupings. It’s part of a system that automatically sorts your incoming website traffic into easy-to-understand categories like Organic Search, Direct, Paid Search, and Referral. The purpose of the Affiliates channel is to specifically isolate and report on the traffic that comes from your affiliate partners.

Think of it as GA4’s attempt to give your affiliate program its own dedicated traffic report. When set up correctly, it allows you to see how many users, sessions, and conversions are being driven by your partnerships. This is incredibly valuable for measuring the ROI of your affiliate efforts without having that data get lost in the sea of general "Referral" traffic.

However, GA4 doesn't magically know which links are from affiliates. It relies on specific clues to categorize traffic correctly, and if those clues are missing, your affiliate data will end up mislabeled.

How Google Analytics Identifies Affiliate Traffic

For Google Analytics to correctly categorize traffic into the Affiliates channel, it looks for some very specific signals, primarily from UTM parameters. If you’re not familiar with them, UTMs are simple tags you add to the end of a URL to tell analytics tools exactly where that traffic came from.

Here’s what GA4's rulebook looks for:

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1. The utm_medium is "affiliate"

This is the most direct and foolproof method. If a link an affiliate uses has utm_medium=affiliate, Google will almost always sort that traffic into the Affiliates channel grouping. It's an explicit instruction that tells GA4, "Hey, this traffic is from a partner."

For example, a properly tagged link would look like this:

https://www.yourwebsite.com/product-page?utm_source=partnerblog&utm_medium=affiliate&utm_campaign=summer_sale

When someone clicks this link, GA4 sees the "affiliate" medium and knows exactly where to put it.

2. The Source Matches Google's Internal List of Affiliate Sites

This method is more of a "black box" because Google doesn't publish this list, but GA4 maintains its own database of well-known affiliate networks and platforms (like ShareASale, CJ Affiliate, Rakuten, etc.). If a user comes to your site from a referring domain that Google recognizes as being an affiliate network, it may automatically classify that traffic as "Affiliates," even if the utm_medium isn't specified.

However, you should never rely on this method. Custom blogs, individual influencers, and smaller publishers used as affiliates likely aren't on Google's list. Relying on this automatic detection means you will miss most of your affiliate data. The best practice is always to enforce consistent UTM tagging across all your partners.

Where to Find Your Affiliates Data in GA4 Reports

Once you have affiliate traffic flowing, you can find it within your standard Acquisition reports. It’s straightforward to track your affiliate performance at a high level.

Here’s a step-by-step guide to locate the data:

1. Log into your Google Analytics 4 property.
2. On the left-hand navigation pane, navigate to Reports > Acquisition > Traffic acquisition.
3. This report shows you where your website traffic is coming from. The main table defaults to the "Primary channel group" dimension.
4. Look for "Affiliates" in the list of channels in the first column of the table.

If you see "Affiliates" in the list, you can click on it to drill down further or see a chart filtered for just that channel. You can then analyze key metrics for your affiliate traffic, such as:

• Users and Sessions: The total volume of traffic from your affiliate partners.
• Engaged sessions: How many visitors from affiliates actually interacted with your site. Low engagement could indicate a mismatch between the affiliate's audience and your content.
• Average engagement time: How long affiliate visitors are spending on your site.
• Conversions: The most important metric! See how many goal completions (e.g., purchases, sign-ups, form submissions) are attributed to the Affiliates channel.
• Total revenue: If you have e-commerce tracking enabled, this column shows the direct financial impact of your affiliate program.

Why Your Affiliate Traffic Isn't Showing Up (Troubleshooting)

One of the most common complaints is, "I know I have affiliate partners, but my 'Affiliates' channel in GA4 is empty!" In almost every case, the problem comes down to improper link tagging.

Here are the top reasons your affiliate traffic isn't being categorized correctly:

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1. Your Affiliates Aren't Using UTMs

If an affiliate simply links to your site with a "naked" URL (e.g., https://www.yourwebsite.com), that traffic will show up under the "Referral" channel. GA4 sees that the visitor came from another website and correctly labels it as a referral, but it has no way of knowing it's a paid partnership.

2. The utm_medium is Incorrect

The tag utm_medium=affiliate is the magic key. Sometimes businesses set up their links with other mediums, such as:

• utm_medium=referral
• utm_medium=partner
• utm_medium=blog_post
• utm_medium=cpc (if they view affiliates as a cost-per-click channel)

While these might make sense internally, GA4 has strict rules. Any utm_medium other than the ones defined by Google will cause the traffic to be sorted into "Referral," "Unassigned," or another category. For clean affiliate tracking, the medium must be affiliate.

3. Inconsistent Tagging Across Partners

Maybe some of your affiliates use the correct tags, but others don't. This leads to fragmented data where a portion of your affiliate traffic is correctly categorized, but the rest is scattered across "Referral" and "Unassigned," giving you an incomplete picture of your program’s performance.

The Fix: Create a standardized UTM link-building guide for your affiliates. Provide them with a simple tool or instructions on how to create tagged links correctly. Proactively check the links on their websites to ensure they are formatted properly.

How to Use GA4 to Optimize Your Affiliate Program

Simply seeing a number under the "Affiliates" channel group is only the first step. The real value comes from digging deeper to see which specific partners are driving meaningful results.

1. Identify Your Top-Performing Affiliates

The main Traffic acquisition report gives you a high-level view. To see which affiliate is sending which traffic, you need to break it down by source.

• Go to the Traffic acquisition report.
• In the table, click the small "+" icon next to the "Session default channel group" column header.
• In the dropdown menu that appears, search for and select "Session source."

This adds a secondary dimension to your report. Now, find the "Affiliates" row, and you will see a breakdown of all the individual sources (your utm_source tags) that drove traffic for that channel. This lets you directly compare partners on metrics like traffic, engagement, and most importantly, revenue.

You can quickly answer crucial questions like:

• "Who is my most valuable affiliate in terms of actual sales?"
• "Which affiliate sends a lot of traffic but has a low conversion rate?"
• "Where should I invest more of my time and commission budget?"

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2. See Which Landing Pages Convert Best for Affiliates

Are your affiliates sending traffic to your homepage or a specific product page? Understanding this can help you optimize the user journey.

• While still in the Traffic acquisition report, add another secondary dimension by clicking the "+" icon again.
• This time, search for and select "Landing page + query string."

Now you can see exactly which of your pages your affiliates are directing their audiences to. If you notice a high-performing affiliate is getting great conversion rates by linking to a specific blog post or product comparison page, you can suggest that strategy to your other, lower-performing partners.

3. Measure Campaign Effectiveness

If you're using utm_campaign in your affiliate links to track specific promotions (like "summer_sale" or "black_friday_2024"), you can also add that as a secondary dimension.

• Add "Session campaign" as a secondary dimension to your Traffic acquisition report.

This lets you see how specific campaigns performed within your affiliate channel. Did that limited-time offer get a lot of traction? Was the holiday promotion a success with your partners? This helps you refine your promotional strategy for future affiliate campaigns.

Final Thoughts

The "Affiliates" channel in Google Analytics 4 is a dedicated feature designed to help you measure the impact of your partner marketing. It's not automatic - it relies heavily on a disciplined approach to UTM tagging. By ensuring every affiliate uses links with utm_medium=affiliate, you unlock clear, consolidated reporting that shows you which partners and campaigns truly drive growth for your business.

We know that managing affiliate performance means pulling data from multiple places: sales from Shopify, HubSpot for lead data, and GA4 for traffic analysis. That's why we built Graphed. We connect directly to all your data sources, allowing you to build real-time dashboards by simply describing what you want to see. Instead of manually cross-referencing affiliate reports with your sales data, you can just ask, "Show me my revenue from Shopify and sessions from Google Analytics by affiliate source for last quarter," and get an instant answer. It turns hours of reporting busywork into a 30-second conversation.