How to Add Secondary Dimension in Google Analytics

Digging into your Google Analytics data can sometimes feel like you’re only scratching the surface. You can see traffic is coming from a certain channel, but which specific campaign was it? You know which pages are popular, but are they more popular on desktop or mobile? Answering these deeper questions is exactly what secondary dimensions are for. This guide will show you how to use this simple feature to add a new layer of detail to your standard GA4 reports and uncover much more meaningful insights.

What Exactly is a Secondary Dimension in Google Analytics?

To understand secondary dimensions, it’s helpful to quickly recap the difference between dimensions and metrics. In Google Analytics, a dimension is an attribute or characteristic of your data. Think of it as the "who, what, and where." Examples include:

• City (e.g., London, Tokyo, New York)
• Device Category (e.g., Desktop, Mobile, Tablet)
• Traffic Source (e.g., google, facebook.com, direct)

A metric, on the other hand, is the quantitative measurement. These are the numbers you use to measure the dimensions. Examples include:

• Sessions (e.g., 2,500)
• Users (e.g., 1,800)
• Conversions (e.g., 150)

Standard GA4 reports let you view your metrics against a single primary dimension. For instance, the Traffic Acquisition report will show you User and Session metrics broken down by the primary dimension of Default Channel Group (Organic Search, Paid Search, Direct, etc.).

Adding a secondary dimension means adding a second column of attributes to drill down further. It splits the rows of your primary dimension into more granular sub-groups, allowing you to cross-reference dimensions and get a more detailed look at your data.

For example, if your primary dimension is City, your report table might look like this:

Primary Dimension: City

• London: 5,000 Users
• New York: 3,000 Users

If you add Device Category as a secondary dimension, the same report transforms into something much more insightful:

Primary: City / Secondary: Device Category

• London / Desktop: 3,500 Users
• London / Mobile: 1,500 Users
• New York / Desktop: 1,000 Users
• New York / Mobile: 2,000 Users

Suddenly, you haven't just identified where your users are, you've discovered how your top locations are accessing your site, revealing that your London audience is mostly on desktop while your New York audience is mobile-first. That’s the kind of information that helps you make smarter decisions.

How to Add a Secondary Dimension in GA4 (Step-by-Step)

Luckily, adding a secondary dimension in a standard Google Analytics 4 report is straightforward. You don't need to build a custom exploration, you can do it right within most tables in the main "Reports" section.

Let's walk through an example using the Traffic Acquisition report.

Step 1: Navigate to Your Chosen Report

From your GA4 dashboard, navigate to the "Reports" section using the left-hand menu. For this example, let's go to "Acquisition" > "Traffic acquisition."

Step 2: Locate the Primary Dimension Column

Once the report loads, you'll see a table where the first column is your primary dimension. In the Traffic Acquisition report, this will be "Session default channel group" by default.

Step 3: Click the Blue “+” Icon

Look directly to the right of the primary dimension’s header ("Session default channel group"). You will see a small blue plus sign ("+"). This is the button to add a secondary dimension.

Step 4: Select Your Secondary Dimension from the Menu

Clicking the "+" icon will open a dropdown menu categorized by different dimension types (Traffic source, Demographics, Platform/device, etc.). Look for and select the dimension you want to add. Let's choose "Device category" under the "Platform / device" group.

Step 5: Analyze Your New, More Detailed Report

The report will instantly refresh and add a new column for "Device category" right next to your primary dimension. Now, instead of seeing just the total users from "Organic Search," you'll see separate rows for "Organic Search / desktop," "Organic Search / mobile," and so on. Your data is now broken down by both channel and device type.

You can follow this same simple process on most other GA4 report tables, like the Pages and Screens report, the Conversions report, or the demographic details report.

High-Impact Use Cases for Secondary Dimensions

Now that you know how to add them, the real power comes from knowing which combinations to use. The key is to start with a question you want to answer about your business.

For E-commerce and Sales

Question: "Which specific sources are driving sales of my top-selling product?"

• Navigate to the "Monetization" > "E-commerce purchases" report.
• Change the primary dimension from "Item ID" to "Item name."
• Add a secondary dimension of "Session source / medium."
• Now, you can see not just which product is selling, but which marketing channels (e.g., "google / organic", "facebook / cpc") are driving the most purchases for that specific item.

Question: "Where are my biggest international spenders located, and what devices are they using?"

• Go to the "User" > "User attributes" > "Demographic details" report.
• Set the primary dimension to "Country."
• Add a secondary dimension of "Device category."
• You might discover that while users from the US drive the most revenue overall, users from Canada shopping on mobile have a significantly higher purchase value per user.

For Content Creators & Marketers

Question: "Which blog post is performing best in organic search compared to organic social?"

• Go to the "Engagement" > "Pages and screens" report.
• Your primary dimension here is "Page path and screen class" which shows your page URLs.
• Add a secondary dimension of "Session default channel group."
• Using the filter bar, you can narrow this report to only show pages in your "/blog/" directory. Now, you can compare how the same article attracts users from Google versus how it attracts them from channels like Facebook or LinkedIn.

Question: "Our traffic is up, but which landing pages are contributing the most new users versus returning users?"

• Navigate to "Engagement" > "Landing page."
• The primary dimension is already set to "Landing page."
• Add the secondary dimension "New / established."
• This combination quickly shows you which pages are your key entry points for attracting new audiences, and which ones are being revisited by your existing users.

For Site Auditing & Technical Checks

Question: "A specific page has a high bounce rate. Is it a technical or design problem on a certain browser?"

• Go to the "Engagement" > "Pages and screens" report and click the page in question.
• This will open a filtered analysis view for that single page.
• Add a secondary dimension of "Browser."
• You might see that a specific page has a stellar engagement rate on Chrome but a terrible rate on Safari for mobile. This is a huge clue that there is likely a design or rendering bug specific to that browser that needs fixing.

A Few Things to Keep in Mind

While an incredibly useful feature, there are a couple of small things to be aware of when you start adding secondary dimensions.

• Data Thresholding & Sampling: In GA4, when you add secondary dimensions with low user counts (like signals-based User Demographics data), you may run into "thresholding," where Google hides some rows to protect user privacy. For very large data sets, GA4 may use a data sample instead of the full dataset. Just keep an eye out for any notices at the top of your report indicating the data has been thresholded or sampled.
• Logical Combinations: Be practical about the combinations you try to build. GA4 won't let you mix user-scoped, session-scoped, and event-scoped dimensions haphazardly for a reason. Ask a clear question first, then choose dimensions that logically help answer it. Crossing "Landing Page" with "Country" is useful, crossing "City" with "Browser Version" might not be.

Final Thoughts

Mastering the secondary dimension is a fundamental step toward moving beyond basic reporting. It’s a simple, fast way to segment your data within standard GA4 reports, providing the extra layer of context you need to turn vague observations into specific, actionable strategies for your marketing, content, or sales efforts.

While these tools within GA4 are powerful for digging into your website data, the bigger challenge is often connecting those insights to data from your other platforms - like your ad accounts, CRM, and email marketing software. Each of those tells a piece of the story, and pulling them all together manually takes hours. That's actually why we built Graphed. After connecting your tools once, you can skip the manual click-and-filter process and instead just ask, “Show me how much revenue last month's Facebook campaign from the UK generated,” and get an answer that pulls in real-time data from both platforms at once.