The Google Analytics 4 custom dimensions limit depends on the level of your account.
In a standard Google Analytics 4 account, you can create up to 50 event-scoped custom dimensions and 25 user-scoped custom dimensions.
In a Google Analytics 4 360 account, you can create up to 125 event-scoped custom dimensions 100 user-scoped custom dimensions.
Check Your GA4 Custom Dimensions Quota
To check whether you have reached Google Analytics 4 custom dimensions limit, follow these steps:
1. Go to your Google Analytics 4 dashboard
2. Click Configure on the left sidebar menu
3. Click Custom definitions
4. Near the top right, click the rectangular button that says “Quota information”
You should now see a summary of your custom dimensions quota. This will tell you how many custom dimensions you have used, and how many slots you have left.
What Happens if I Reach My GA4 Custom Dimensions Limit?
If you reach any of those limits, you can delete custom dimensions in GA4. (This is also known as archiving custom dimensions.)
Prioritize Your Custom Dimensions
While every Google Analytics 4 event parameter can be a custom dimension, that doesn’t mean it should be.
In fact, at some point you’ll probably have more than 50 custom parameters. (Fifty being the custom dimensions limit for GA4 standard accounts.)
So how do you decide what should be a custom dimension and what shouldn’t? Ask yourself these two questions:
What custom dimensions already exist, and am I utilizing them property?
Before creating a new custom dimension, first make sure there isn’t already one available that would serve your purpose.
My favorite way to do this is in the Explore section of GA4. You can access it in the left sidebar menu:
Open a “Free form” report and click the + sign next to DIMENSIONS in the Variables column.
You will now see a popup that tells you how many total, custom and predefined dimensions are available to use in your reporting.
Peruse these existing dimensions either by opening and scrolling through the various categories, and/or by using the search function at the top of the page.
How do you know the definition of a GA4 dimension?
Most (but not all) dimensions are dotted-underlined, which indicates that if you hover over them, their definition will pop up. (This is why it’s important to give a good description when creating custom dimensions in Google Analytics 4.)
If you don’t see a description for a particular parameter, Google it for more information. (Hopefully, most of their definitions can be determined with a little common sense.)
Once you are more familiar with existing dimensions – both predetermined and custom – you can decide whether it’s necessary to create another one.
The following question is a great way to answer that.
What data is missing from my reports that I wish I had?
When I say reports, that could mean your standard GA4 reporting dashboard, your Explore dashboard or even Google Data Studio.
If you’re looking through your data on a regular basis and something is lacking, it may be time to create a new custom dimension.
Assuming you already completed the previous step of researching your existing dimensions, this should be a straightforward decision. (So long as you haven’t exceeded your limit, as discussed above.)
Of course you can’t analyze data that’s not being collected. First determine if it should be an event or a parameter.
If you decide event, it will show up in your reports as soon as its live.
If you decide parameter, then you will indeed need to create a custom dimension.
Custom Dimensions Google Analytics 4: Summary
Custom dimensions in Google Analytics 4 are based on the parameters for your events.
They’re pieces of information associated with those events.
To analyze data associated with a parameter, you have to create a custom GA4 dimension for it.