What are custom dimensions in GA4? Easy-to-understand explanation of how to use and set up

However, for those who have migrated from UA to GA4, it may be difficult to understand the differences in custom dimension content and setting methods between UA and GA4, and they may not be able to make good use of it.

In this article, for those who want to manage and analyze their own data with GA4, we will explain how to set custom dimensions, how to use them, and points to note when setting them . Please use all means.

Table of contents

GA4’s custom dimension is a function that allows you to set your own analysis axis for data other than events automatically collected by GA4 and analyze it in a report . Unlike UA, you can assign any name to it, making it easier to check data when analyzing reports.

There are also differences in how it works with BigQuery (a service that processes vast amounts of data on Google’s cloud) and how raw data is obtained. In order to get raw data with UA, it was necessary to work with BigQuery for a fee.

GA4 works with BigQuery for free, allowing you to directly retrieve and analyze raw data. However, when exporting to BigQuery, it should be noted that the name of the custom dimension set in GA4 is not reflected, and the data itself for which the custom dimension is set must be checked.

In UA, there were four types of scopes: “User”, “Session”, “Hit” and “Product”. On the other hand, GA4 has two types of scope (measurement range): event scope and user scope. In other words, the two realities that custom dimensions measure are user properties and event parameters, which are also exported to BigQuery as user properties and event parameters.

About event scope

Event scope (hit scope) is a custom dimension that is set when performing analysis based on a specific event .

For example, if you want to analyze based on the number of views of the member registration page, set the event parameter of “member registration page viewing event”. This allows you to aggregate the number of sessions by the number of views of the member registration page.

About user scope

User scope is a custom dimension that is set on a per-user basis. For example, you can specify static (permanent) attributes of a user like [spender=true], [birth=date of birth], [member_rank=member rank].

Custom dimensions play an important role when analyzing in the report screen. UA data used to be managed by numbers, but with custom dimensions, it is possible to assign easy-to-understand names, making management easier.

In addition, by adding custom dimensions, offline and online data are integrated, making it possible to acquire and analyze more niche information than ever before, such as analyzing purchase behavior in real life and on the web.

However, please note that UA’s custom dimension settings are not carried over to GA4. For example, if there are event parameters set in the UA, data cannot be obtained in the discovery report as they are. You need to redefine the event scope custom dimension on GA4 .

GA4 allows you to set the numerical values ​​to be analyzed using custom indicators . You’ll get even more granular data with your own setup using custom dimensions and custom metrics.

Event parameters are required when configuring custom metrics. Use event parameters recommended by Google. Custom metrics default to the event parameter name, so if the name is confusing, change it to something more descriptive.

Google recommended event parameters can be found here.

Custom metrics also allow you to set detailed metrics such as bounce rate and average session duration.

From here, we will introduce how to use custom dimensions with examples. We will explain everything from creating custom dimensions to GTM event measurement settings and analysis methods using reports.

① Create a custom dimension in GA4

Editor permissions are required to create custom dimensions. After obtaining the authority, make the following settings from the management screen.

You can change the dimension name to something meaningful.

1. Select [Settings]
2. Select [Custom Defined]
3. Select Create Custom Dimension
4. Write the dimension name and parameters in the new custom dimensi

<Custom dimension setting example>

(2) GTM event measurement settings

GTM (tag manager) settings are required to measure data with GA4 . Configure settings to send event data from GTM to GA4 when an event you want to measure occurs.

For GTM settings, set the parameters created by custom definition. GTM does not distinguish between custom dimensions and custom indicators, so please set only the parameters. If you have already set parameters and measured with GA4, you do not need to change GTM.

(3) Analysis on the report screen

By using custom dimension reports, you can perform analysis for site improvement in more detail than before. This section explains how to use the search report as an example.

After confirming the event measurement for the number of clicks on the report screen, display the event measurement in a free-form report from [Search] in GA4. There are 6 types of templates available for exploration reports. Let’s try creating a free-form table first to get the hang of it.

In free-form reports, data on the right reflects data settings customized on the left side of the screen. If you want to create a table, add the dimensions and indicators you want to analyze in the settings column on the left, import the data, and the table will be displayed.

Keep the following points in mind when setting up custom dimensions :

A basic point to note is whether it is necessary to set custom dimensions in the first place. GA4 has default analysis axes, so that function alone may be sufficient for data analysis.

Here are three points to confirm the need for custom dimension settings.

There is a limit to creating custom dimensions

In GA4, the number of custom dimensions has increased compared to UA, but the number is different for each scope and the upper limit is set. Event-scoped custom metrics also have limits. User-scoped custom metrics cannot be registered in the first place, so the upper limit is not an issue.

• Event scope custom dimensions: 50
• User-scoped custom dimensions: 25
• Event scoped custom metrics: 50
• UA custom dimensions: 20 total across all scopes

If you exceed each limit, you can create new custom dimensions by archiving the ones you don’t need.

data is not reflected immediately

After setting custom dimensions, there are cases where the settings are not reflected immediately . The Google Analytics help clearly states that for the first 48 hours , a value of “(unset)” will be displayed for custom dimensions .

Similarly, it also states that it can take 24-48 hours for data to be entered for custom metrics. If it is not reflected, wait a while and check again.

Custom dimensions cannot be deleted

According to Google Analytics Help , it states that custom dimensions and custom indicators cannot be deleted . However, you can manage and edit their content and disable features. Uncheck the [Active] check box on the management screen and save the settings.

The measurement range is different from GA4’s Custom Dimension UA, and it is a function that allows you to set your own analysis axis apart from the default dimension. In addition, with custom indicators, you can independently determine the numerical values ​​to be analyzed, so using both makes more detailed measurement and analysis possible. However, UA’s custom dimension settings are not carried over to GA4, so let’s set them again in GA4.

You can check the analysis result by custom dimension from the report. Please select the type of report as necessary and utilize it for data analysis.

Understanding custom dimensions and setting them correctly will broaden the range of analysis and provide better quality measurement data. Please refer to this article to set custom dimensions and use them for site analysis.