Google Analytics: Setting Custom Dimensions for Custom UTM Parameters

Custom UTM Parameters

Google Analytics (GA) collects a lot of data. However, most of that data is only suggestive. Analyzing and drawing suggestions from so much data is hard. Only a small fraction of it will help you make better decisions.

If you feel limited by the standard Google Analytics reports, you should consider modifying the data Google Analytics collects. One of the best ways to do this is by using custom dimensions and custom UTM parameters. Combine these two together and you’ll be able to get granular data that default dimensions and UTM parameters don’t provide.

Key Takeaways

  • UTM parameters correspond to a dimension in Google Analytics. For example, the value in the UTM parameter, &utm_content= adds detailed data to the dimension  Ad Content.
  • Custom UTM parameters are a subset of the many different custom URL parameters that exist. Another example would be custom URL parameters generated with Google Ads.
  • Use a custom UTM parameter when you want to collect data that does not fit in the default parameters Google provides. We’ve seen clients use custom UTM parameters in many interesting ways, including tracking affiliate performance, identifying how different ads perform based on geo-locations, and comparing the performance of two or more agencies.
  • For GA to figure out what to do with the custom UTM parameters that you build, you’ll need to create a corresponding GA custom dimension. This is the only way for you to drill down into the important metrics necessary for analyzing marketing campaign performance.

How URL Parameters and Dimensions in Google Analytics Are Connected

Dimensions are one of the building blocks of any Google Analytics report. Whenever GA collects website data, it categorizes it by relevant dimensions and metrics.

A Google Analytics acquisitions report with the dimensions on the left and the metrics for these dimensions to the right
A Google Analytics acquisitions report with the dimensions on the left and the metrics for these dimensions to the right

UTM tags, on the other hand, allow you to add more specific details to dimensions as a way to further refine the data gathered for GA reports. By adding UTM tags at the end of your website links, you get details about your traffic and make the dimensions more meaningful.

So when you look at dimensions in the acquisition reports, you’ll notice that each UTM tag corresponds to a specific primary dimension.

The five UTM parameters and where the value in each UTM parameter goes in GA Dimensions
The five UTM parameters and where the value in each UTM parameter goes in GA Dimensions

Now here’s the thing:

At some point, you might want to get information about your traffic that can’t be categorized by any of the five UTM tags for dimensions. That’s when you need custom UTM parameters.

Build custom UTM parameters with ease.

Just one click and you can create a custom UTM link.

Why Set Up Google Analytics Custom Dimensions for Custom URL Parameters Such as Custom UTMs

You can build a custom UTM parameter without creating a corresponding custom dimension for it. However, this will limit how you see the data in Google Analytics because you won’t be able to report on that parameter.

Essentially, GA will record it as a visited page but it will have no way of knowing how to connect that information to the metrics that you want to track. The only way for Google to appropriately attribute data that’s coming in with that custom UTM parameter is for you to set up a corresponding custom dimension.

For example, let’s say you want to track and measure influencer marketing campaigns. You build a custom UTM parameter &influencer=, for this. 

You build one for Betty Bailey.

And another one for Brandon Bailey.

If you build this custom UTM parameter WITHOUT a custom dimension for it, GA will register it but the reporting you get about that click will be limited.

You’ll see it recorded as a visit, but you won’t find detailed information about it under the acquisitions section. 

You’ll know that someone has clicked the link and visited the page on your site by going to the behavior section of GA. But you won’t find that detail under the campaign reports — which defeats the purpose of using it as a UTM in the first place.

A custom UTM parameter without a custom dimension is tracked as a visited page. However, you won’t find it in the acquisitions section, which is critical for analyzing campaign performance
A custom UTM parameter without a custom dimension is tracked as a visited page. However, you won’t find it in the acquisitions section, which is critical for analyzing campaign performance

This is why whenever you build a custom UTM parameter, you should build a custom dimension for it, too.

This is the only way Google Analytics can understand what the custom UTM means and what to do with the values in it. With this info in hand, GA can measure correctly, and you can get insights on ROI, traffic behavior, or conversion rates.

You have access to this data in different places in Google Analytics. You’ll find it as

  1. Secondary dimensions under acquisitions
  2. Primary dimensions in custom reports and segments

The Limitations of Custom Dimensions in Google Analytics

Setting custom dimensions in Google Analytics requires some strategy.

Gather only the data that default GA dimensions don’t already measure as well as data that you’re certain is relevant to your main business metric.

Google Analytics custom dimensions have some limitations so you shouldn’t just build them randomly without any advanced planning:

  1. Each Google Analytics property is allowed only 20 custom dimensions (200 for GA 360). These are enough for most businesses especially when you make a conscious and intentional effort to define and identify what matters the most to your business KPIs. If you don’t, you might end up building custom dimensions that you either don’t need or don’t contribute towards data that will help move your business forward.
  2. Custom dimensions can not be deleted. You can only make them inactive if you don’t need them anymore.
  3. Custom dimensions can be complicated to set up. Creating custom UTM parameters, building a custom dimension for them, and then configuring Google Tag Manager (GTM) requires a specific level of familiarity, or analytics consulting.

How Custom UTM Parameters and Custom Dimensions Improve Data in Google Analytics

When you build custom UTM parameters and custom dimensions together, what you’re interested in is being able to add tiny details for traffic or attribution data that are not already tracked by GA.

Google Analytics Dimensions and Metrics Explorer page shows you the default dimensions for traffic sources.

The list of default dimensions for Traffic Sources
The list of default dimensions for Traffic Sources

When you want to track data that Google Analytics has not already predefined, as seen above, that’s when you consider using a custom UTM parameter.

For example, let’s say you want to compare the performance of your affiliates. You want to know who among your affiliates turns more trial users into buyers. Or which channel performs the best for each affiliate. Or maybe you’re running branded deals and you want to find out which affiliate has the best ROI.

Looking at the Dimensions Explorer above, you’ll see that affiliate ID is not a dimension in GA. So you would need to set up a custom UTM parameter for this and then build a custom dimension in GA for that parameter. Then you’ll give each of your affiliates their unique name or ID that they use whenever they link to your site.

When you set up a custom dimension, you’re telling Google Analytics to add a new category (dimension) in your data. And that the value that goes into that category will come from the custom UTM parameter that you set.

With this additional data Google Analytics tracks, you can then easily report on the performance of your affiliates without necessarily using another tool outside of GA. Alternatively, you can connect this to your affiliate management tool to amplify the data.

As you can see, custom UTM parameters and custom dimensions are very useful for cases like this.

We’ve noticed that you’ll most likely use custom UTM parameters when you want to add nuance to your reports about the performance of:

  • External agency
  • Geo location
  • Offline marketing campaigns like direct mail, billboards, or magazine ads
  • Influencers and affiliates
Default UTM parameters along with some custom ones: utm_placment, utm_creative, utm_targeting, utm_adgropu, utm_product, utm_brand, utm_adname

Where to Set Up Custom Dimensions in GA

There are two steps to set up custom dimensions. First, you need to create a custom dimension in GA. Then, you set up Google Tag Manager so that it recognizes that custom dimension and knows what to do with the collected data and that dimension.

Tip: Before setting up custom dimensions and custom UTM parameters, sit down with your team to plan, research, and understand what additional custom UTMs you will need. As usual, naming conventions help with ensuring consistency and data reliability.

Setting up custom dimension in Google Analytics

  1. Go to Admin. Select Property, Custom Definitions, and then Custom Dimensions. 
  2. Click Add New Custom Dimension. Add the name of the custom UTM parameter. Under Scope, there are four to choose from. But for attribution purposes,  the scope would either be Session or User.
    • Session attributes the value for the whole time a visitor is in your site. That is, from when they arrive to when they leave the site. If they visit the site again — provided it’s more than 30 minutes from the last visit — the new visit will be tagged as a new session.
    • User is attributed to the person visiting the site. They’re given an ID and their behavior every time they visit will be recorded and attributed to that user ID.
  3. Click the box to set the custom dimension to active. Then click Publish.
  4. Important: Remember the custom dimension’s index number as you’ll need it in the next step.

Configuring Google Tag Manager

After creating a custom dimension, the next step is to ensure Google Tag manager knows about that dimension.

  1. Go to Google Tag Manager and click the corresponding property.
  2. Go to Variables, select User Defined Variables, and click New.
  3. Name the variable so that it’s easy for anyone to understand that it corresponds to the custom dimension in GA.
  4. Next, click the pencil icon at the top right and choose the variable type ‘Google Analytics Settings.’
  5. In the window that opens, add your tracking ID. Then click ‘More Settings’ and then click Custom Dimension’. Then ‘Add Custom Dimension’.
  6. Fill out the index field with the custom dimension index number. For the Dimension Value, click the variable icon. Then click the plus icon at the top right on the window that slides from the right.
  7. Next, click ‘Choose a variable type to begin setup’. Then click the variable type ‘URL.’
  8. Then in ‘Component Type,’ choose ‘Query’ in the dropdown menu.
  9. In the field for ‘Query Key,’ add the name of the custom UTM parameter.
  10. Lastly, give the Dimension value a name and click Save.

For full detail on the steps, go to Google reference for custom Google Analytics dimensions in GTM.

Where to Set Up Custom UTM Parameters in GA

For Google Analytics to know what values to add to the custom dimensions, you’ll also need to ensure that the custom UTM parameters are correctly set up and that they line up with the custom dimensions.

To easily do this, you can build custom UTMs with a UTM builder tool like

The premium version of makes it very easy to build a custom URL parameter that you can specify before creating a custom dimension in Google Analytics
The premium version of makes it very easy to build a custom URL parameter that you can specify before creating a custom dimension in Google Analytics.

Side note: It doesn’t matter what you build first. Custom UTMs or custom dimensions. Just make sure that when you’re setting up Google Tag Manager, the query key is the same name as the custom UTM parameter you built.


Building custom UTM parameters and custom dimensions is not for everyone. They’re complicated to set up and it’s easy to make a mistake if you’re not familiar with the steps involved.

Using a UTM builder tool like helps make the process much quicker and easier. You’ll still need to know how to set them up in Google Analytics and Google Tag Manager, but if you follow the steps above, you should be able to do this in no time.

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Hamed Kian

Hamed is an experienced Digital Marketer benefiting from a multidisciplinary education in Engineering, MBA, and Ph.D. in Business Administration (Candidate). He has extensive experience providing web analytics solutions including strategic planning for data collection, data collection, data processing, reporting, activation, and analysis. He also has experience leading conversion optimization projects from conversion research, test ideation, prioritization, implementation, and analysis.

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