This guide will explain how to save the GCLID parameter of a user’s Google Ads click in GA4. There are many ways to save the GCLID parameter, and storing it in GA4 reports will make it easier for us to analyze advertising data more comprehensively.
What is GCLID?
GCLID is Google’s click identifier and is a key element to successfully tracking Google advertising performance. It associates users with the clicked ads, ad groups, campaigns, keywords, etc. Every time someone clicks a Google Ads link, Google appends a unique GCLID value to the destination URL, so every conversion can be traced back to the exact ad, campaign and keyword that produced the click.
Why should GCLID be stored in GA4?
The core function of the GCLID parameter is to measure the conversion performance of Google Ads ads, and GA4 can successfully identify Google Ads traffic in its attribution reports.
GA4 has its own attribution path report, which will show you how various channels work together if a user visits the website multiple times from multiple different sources before converting. Collecting the GCLID parameter as a user-scoped custom dimension in GA4 means that once the user is associated with the GCLID, you will know that they came in through Google Ads, and any future conversions can be linked to Google Ads.
What you need before you start
- A Google Ads account with auto-tagging enabled (this is what puts the gclid parameter into your click URLs)
- A Google Analytics 4 property where you want the GCLID data to appear
- Google Tag Manager installed on your website (or any tag manager you prefer)
How to save GCLID in GA4 via Google Tag Manager
Step 1: Enable auto-tagging in Google Ads
First, you need to enable auto-tagging in Google Ads. When a user clicks your ad and enters the website, the GCLID parameter will be appended to the URL. To verify this, go to Google Ads → Tools & Settings → Conversions and make sure Auto-tagging is switched on.
Step 2: Create a URL query variable in GTM
We can use Google Tag Manager to capture the value of any URL parameter and send it to any data collection point. In this case, we will send the GCLID parameter to GA4 reports.
- In GTM, create a new variable – select URL for variable type, select query for component type, and enter gclid for query key
- Give the variable a clear name (for example
GCLID Value) so you can reuse it across tags
Step 3: Set up the GA4 event tag
Set up GA4 tag event code: Create a new event called “gclid_pickup” and send the new variables above as user properties to GA4.
Step 4: Add a trigger
Trigger for this tag: The page URL contains “gclid”, so it will only trigger if there is a gclid parameter in the URL.
Step 5: Register the custom dimension in GA4
The final step is to create a new user-scoped custom dimension within GA4. Without this you will not see gclid data reported in your GA4 reports.
In GA4, go to Admin → Custom definitions → Create custom dimension, set the scope to User, and use exactly the same name you set for the user property in GTM (for example gclid_pickup). Note that a brand-new custom dimension can take up to 24–48 hours before it starts to appear in GA4 reports.
How to verify GCLID is being collected
- Use GTM Preview mode: open a test URL that contains
?gclid=test123and confirm thegclid_pickuptag fires. - In GA4, open Reports → User → User attributes and check whether the GCLID dimension records values after real ad clicks.
- Click a live Google Ads ad and inspect the landing URL to confirm a
gclidparameter is present.
FAQ
Can I collect GCLID without Google Tag Manager?
Yes. You can read the gclid parameter with a small JavaScript snippet or with a server-side setup, but GTM is the simplest no-code method and keeps all your tracking configuration in one place.
Why is my GCLID data empty in GA4 reports?
The most common causes are: auto-tagging is disabled in Google Ads, the custom dimension name does not exactly match the user property name in GTM, or the dimension was created less than 24 hours ago.
Does GCLID improve Google Ads conversion tracking in GA4?
Yes. When GCLID is captured as a user-scoped dimension, GA4 can link later conversions back to the original Google Ads click, which makes your paid attribution reporting noticeably more accurate.
Does GCLID tracking work with a Google Ads agency account?
Yes. Auto-tagging and GCLID capture behave exactly the same in a Google Ads agency account as in a standard account. Advertisers who need higher spending limits often buy an agency ad account and then follow this same GTM setup to keep conversion tracking accurate.