GCLID

GCLID stands for Google Click Identifier. It is a unique code that Google Ads adds to your landing page URL each time someone clicks an ad, through a feature called auto-tagging. The GCLID lets Google match that exact click to later activity, such as a conversion or a session in Google Analytics.

Why GCLID Matters

GCLID is how Google Ads and GA4 talk to each other. When auto-tagging is on, Google appends a GCLID to every ad click. That single value carries the campaign, ad group, keyword, and creative behind the click. GA4 reads it to label the visit as Google / CPC automatically, with no manual UTM tagging needed.

The GCLID also enables offline conversion import. If a lead from a Google ad becomes a sale in your CRM, you upload the stored GCLID with the conversion. Google then credits the exact click that started the journey. This feeds Smart Bidding, which uses real conversion data to set bids. Clicks must be imported within 90 days for the match to work.

How GCLID Works

The process runs automatically once auto-tagging is enabled:

1. A user clicks a Google ad. Google appends a GCLID to the destination URL.
2. The landing page reads the GCLID and stores it, usually in the _gcl_aw first-party cookie, which lasts about 90 days by default.
3. The user converts. The GCLID is captured with the conversion or passed into a form and your CRM.
4. Google receives the GCLID through conversion tracking or offline import and matches it to the original click.

A GCLID-tagged URL looks like this:

https://linkutm.com/?gclid=Cj0KCQjw_abc123XyZ

GCLID vs UTM

A GCLID and a UTM are not the same thing. A UTM is readable text you write yourself, like utm_source=google&utm_medium=cpc. GA4 reads UTMs to classify traffic from any channel. A GCLID is an opaque code Google generates and reads to optimize bids and import conversions.

	GCLID	UTM
Created by	Google Ads, automatically	Marketer, manually
Read by	Google Ads (and GA4 linking)	GA4 and analytics tools
Readable	No (random string)	Yes (plain words)
Scope	Google Ads only	Any channel

For Google Ads, auto-tagging with GCLID is enough and Google recommends it over manual UTMs. For other channels like email or social, you still need UTM parameters. GCLID is one specific type of click ID; Meta uses FBCLID and Microsoft uses MSCLKID.

GBRAID and WBRAID

GBRAID and WBRAID are Google’s privacy-safe alternatives to GCLID. After Apple’s App Tracking Transparency changes in iOS 14.5, Google could not always set a GCLID for iOS traffic. GBRAID handles app-to-web and in-app conversions. WBRAID handles web conversions when a GCLID is unavailable. They work like GCLID but aggregate data to protect user privacy.

How to Find or Enable GCLID

Click one of your own Google ads and look at the URL in the address bar. If you see gclid= followed by a long string, auto-tagging is working. If it is missing, turn auto-tagging on in Google Ads under Account Settings. Most accounts have it enabled by default.

Frequently Asked Questions

What does GCLID stand for?

GCLID stands for Google Click Identifier, sometimes called the Google Click ID. Google Ads adds it to landing page URLs through auto-tagging. It uniquely identifies a single ad click.

What is the difference between GCLID and UTM?

GCLID is generated automatically by Google and read by Google to optimize bids and import conversions. A UTM is written manually and read by GA4 to label traffic from any channel. GCLID is a random string; a UTM uses readable words.

How long does a GCLID last?

The GCLID itself does not expire, but the _gcl_aw cookie that stores it lasts about 90 days by default. For offline conversion import, you must upload the GCLID to Google within 90 days of the click.

Do I need GCLID and UTM together?

Not for Google Ads, where auto-tagging with GCLID covers reporting. You still need UTMs for non-Google channels like email, social, and referral links, since GCLID only applies to Google ad clicks.

To tag campaigns that auto-tagging does not cover, build clean links with the free UTM builder at linkutm.