What is a Medium in Google Analytics?

Seeing "Medium" in your Google Analytics reports tells you how users arrived on your website. Understanding this simple dimension is the key to accurately measuring your marketing performance. This article breaks down exactly what a Medium is, what the common values mean, and how you can take control of your tracking to get clearer insights.

What Exactly is a Medium in Google Analytics?

In Google Analytics, the Medium is the general category of a traffic source. Think of it as the delivery mechanism. If a user clicked a link to get to your site, what type of link was it? Was it an organic search result, an email newsletter link, or a paid ad? The Medium answers this question.

It's one half of a critical pair of dimensions: Source and Medium. Together, they give you the full story of your traffic.

Source: Who sent you the traffic? (e.g., google, facebook, newsletter_q4)
Medium: How did they send it? (e.g., organic, social, email)

Source vs. Medium: An Easy Analogy

This is the most common point of confusion for new GA users. Let's make it simple.

Imagine you're driving to a friend's house. Your friend asks, "How did you get here?"

Your Medium would be the type of transportation: "by car."
Your Source would be the specific origin: "from my office."

In the digital world, it works the same way:

A user arrives "by organic search results" (Medium) from "google.com" (Source).
Another user arrives "via a paid social ad" (Medium) from "facebook.com" (Source).

When you see them paired together in GA4, like google / cpc, you're looking at the Source (google) and the Medium (cpc, for 'cost per click'). This tells you the traffic came from a paid Google ad. Seeing google / organic means it came from an unpaid Google search result.

GA4's List of Default Mediums (Channels)

While you can see specific Mediums like "cpc" or "organic," Google Analytics goes a step further by bundling common Source/Medium combinations into high-level categories called Default Channel Groups. You’ll see these in your main acquisition reports.

Understanding these channels is crucial because they're how Google organizes your traffic out of the box. Here are the most common ones and what they mean.

What Does "Organic Search" Mean?

This channel groups any traffic that arrives from clicks on unpaid search engine results. It's one of the most important channels for measuring SEO performance.

Common Source/Medium Pairings: google / organic, bing / organic, duckduckgo / organic

What Does "Paid Search" Mean?

This is traffic from your paid search engine ads, like Google Ads or Microsoft Ads. GA recognizes this when ad platforms and GA are linked, or when the destination URLs are tagged correctly.

Common Source/Medium Pairings: google / cpc, bing / cpc, google / paid

What Does "Direct" Mean?

This channel is for traffic where Google Analytics couldn't identify another referring source. This happens when a user types your URL directly into their browser, uses a browser bookmark, or clicks a link from a non-web source (like a PDF or mobile app).

Common Source/Medium Pairings: (direct) / (none)

What Does "Referral" Mean?

This is traffic that comes from a click on another website that isn't a search engine or a known social media platform. Think of it as another site "referring" traffic to you. This is common if you're mentioned in a news article or listed on a partner's website.

Common Source/Medium Pairings: nytimes.com / referral, some-blog.com / referral

What Does "Organic Social" Mean?

This includes traffic from clicks on unpaid links from social media platforms. GA maintains a list of sites it recognizes as social media (like Facebook, Twitter, Instagram, LinkedIn, etc.).

Common Source/Medium Pairings: facebook.com / social, t.co / referral (t.co is Twitter's URL shortener)

What Does "Paid Social" Mean?

Just like Paid Search, this is a category for traffic coming from paid campaigns on social media platforms. For GA to recognize this cleanly, you must tag your ad URLs correctly.

Common Source/Medium Pairings: facebook / cpc, linkedin / paid

What Does "Email" Mean?

Traffic from links in an email. This is almost always something you have to set up yourself using custom tracking URLs (more on that below). If you don't tag your email links, this traffic will likely show up as 'Direct'.

Common Source/Medium Pairings: newsletter / email, klaviyo / email

Dealing with "(Not Set)" and "(None)" as a Medium

Seeing messy data like "(not set)" or "(none)" is frustrating but common. Here’s what these values usually mean and how to fix them.

Why Does My Medium Say "(None)"?

A Medium of (none) is almost always paired with a Source of (direct). It signifies that GA4 has no data on how the session arrived. It’s the traffic Google can't attribute to a specific channel. As mentioned before, this includes:

Users directly typing your URL.
Users clicking a browser bookmark.
Clicks from non-secure (HTTP) pages to secure (HTTPS) pages.
Clicks from links in desktop software, PDFs, or mobile apps.
"Dark social" traffic from platforms like Slack, WhatsApp, or text messages.
Untagged links in your email campaigns.

You can't eliminate (direct) / (none) traffic, but you can reduce it by diligently tagging your marketing campaigns.

Why Does My Medium Say "(Not Set)"?

The value (not set) means Google Analytics collected data for the session but received zero information for the Medium dimension. This typically points to a tracking problem. The most common cause is using manual UTM tagging but failing to include the utm_medium parameter. For example, you might create a link with utm_source and utm_campaign, but if you forget utm_medium, GA will show (not set).

How to Take Control with UTM Tracking Codes

The best way to ensure clean, accurate source and medium data is to manually tag the URLs for your marketing campaigns. You do this using UTM (Urchin Tracking Module) parameters. These are simple tags you add to the end of a URL to tell Google Analytics exactly where the click came from.

There are five standard UTM parameters, but for our purposes, we're focused on two:

utm_source: The specific originator of the traffic (e.g., summer-sale-email).
utm_medium: The general category of the traffic (e.g., email).

When you combine them, a URL looks like this:

https://www.yourwebsite.com/?utm_source=facebook&utm_medium=paid-social&utm_campaign=black-friday-promo

When someone clicks that link, Google Analytics will know the traffic came from the "facebook" source and the "paid-social" medium. No guesswork required.

How to Easily Create UTM Codes

You don't need to build these URLs by hand. Google provides a free Campaign URL Builder tool that makes it incredibly simple.

Enter your website URL.
Fill in the campaign parameters. At a minimum, always use utm_source, utm_medium, and utm_campaign.
The tool generates the full, tagged URL for you to copy and use.

Best Practices for UTM Mediums

Be Consistent: Decide on a convention and stick to it. Whether you use social or paid-social, use the same one every time. Inconsistency leads to messy reports.
Use Lowercase: Email and email will show up as two separate mediums in your reports. Stick to lowercase to keep things clean.
Use Dashes, Not Spaces: Use hyphens for multi-word mediums like paid-social instead of spaces.
Keep a Spreadsheet: For teams, it's a great idea to maintain a shared spreadsheet to document what Source, Medium, and Campaign names you use for different initiatives. This ensures everyone is on the same page.

How to Find Medium Data in GA4 Reports

Finding this information in Google Analytics 4 is straightforward. The primary place to look is in the Acquisition reports.

Navigate to Reports in the left-hand navigation.
Under the Life cycle section, click on Acquisition.
Go to the Traffic acquisition report.

By default, this report is grouped by the "Session default channel group." This gives you that high-level overview. To see the specific mediums, you have two options:

Change the Primary Dimension: Click the drop-down arrow above the first column (where it says "Session default channel group") and select Session medium.
Add a Secondary Dimension: Click the plus (+) sign next to the Primary Dimension drop-down and select Session medium from the list. This lets you see the Medium alongside the Default Channel Group, providing even more context.

For more advanced analysis, you can build a custom report in the Explore section, using Medium as a primary dimension in any visualization you create.

Final Thoughts

Mastering the Medium dimension is a crucial step towards understanding your marketing performance. It's the "how" behind your website traffic, telling you which marketing channels are successfully sending users your way. By using UTM codes to keep your data organized, you can move from guesswork to making decisions with clear, reliable information.

Jumping between Google Analytics, your various ad platforms, and email marketing software to piece this story together can be exhausting. That's why we created Graphed. We connect directly to your data sources like Google Analytics, ads platforms, and your CRM, so you can stop manually exporting CSVs. Simply ask a question in plain English, like "Show me a chart of sessions by medium over the last 90 days," and get a live dashboard in seconds without needing to learn a complex BI tool.