Auto-Tagging
Auto-tagging is a Google Ads feature that automatically adds a unique tracking parameter, the GCLID, to the URL of every ad click. It removes the need to tag Google Ads links by hand. The GCLID lets Google match each click to later activity, such as a conversion or a session in Google Analytics 4.
Why Auto-Tagging Matters
Auto-tagging is how Google Ads connects an ad click to what happens next. When it is on, Google appends a GCLID to each click and passes far more detail than manual tags can carry. That includes keyword, ad group, match type, device, and the final URL the user reached.
This data powers conversion tracking, GA4 reporting, and Smart Bidding. Smart Bidding uses real conversion data tied to each GCLID to set bids automatically. Without auto-tagging, those signals are missing and bid strategies perform worse.
Auto-tagging is on by default for Google Ads accounts. Google recommends keeping it enabled. It also enables offline conversion import: if a click becomes a sale in your CRM, you upload the stored GCLID and Google credits the exact click that started the journey.
How Auto-Tagging Works
The process runs automatically once the setting is on:
- A user clicks a Google ad. Google appends a GCLID to the destination URL.
- The landing page loads. Google Analytics or the Google Ads tag reads the GCLID and stores it in the
_gcl_awfirst-party cookie, which lasts 90 days by default. - The user converts. The GCLID is captured with the conversion, or passed into a form and your CRM.
- Google receives the GCLID through the linked account or offline import and matches it to the original click.
A GCLID-tagged URL looks like this:
https://example.com/?gclid=Cj0KCQjw1JeYBhDxARIsAO
On iOS devices affected by App Tracking Transparency, Google appends WBRAID or GBRAID instead of a GCLID. Microsoft Advertising runs its own auto-tagging that adds an MSCLKID.
Auto-Tagging vs Manual UTM Tagging
Auto-tagging and manual UTM tagging solve different problems. Auto-tagging applies only to Google Ads clicks and uses an opaque GCLID. Manual tagging means adding readable UTM parameters yourself, and it works on any channel.
| Auto-Tagging (GCLID) | Manual UTM Tagging | |
|---|---|---|
| Created by | Google Ads, automatically | Marketer, manually |
| Read by | Google Ads and GA4 | GA4 and any analytics tool |
| Readable | No (random string) | Yes (plain words) |
| Scope | Google Ads only | Email, social, organic, ads |
The two are not mutually exclusive. Many teams keep auto-tagging on for Google Ads and add UTMs on top for granular campaign labels. If both appear on a URL, GA4 lets you choose whether the GCLID or the manual UTM values take precedence. For Google Ads specifically, a tool like the Google Ads UTM builder adds clean UTMs alongside the auto-tagged GCLID.
How to Enable or Check Auto-Tagging
Click one of your own Google ads and look at the URL in the address bar. If you see gclid= followed by a string, auto-tagging is working.
To check the setting, open Google Ads, go to Admin, then Account settings, and find Auto-tagging. Confirm the box “Tag the URL that people click through from my ad” is selected. Most accounts have it on by default, but it can be turned off during migrations or by older account configurations.
Frequently Asked Questions
What is auto-tagging in Google Ads?
Auto-tagging is a Google Ads setting that automatically adds a GCLID parameter to the URL of every ad click. It lets Google track conversions, populate GA4 reports, and feed Smart Bidding without any manual tagging. It is enabled by default on most accounts.
What is the difference between auto-tagging and manual UTM tagging?
Auto-tagging is automatic, applies only to Google Ads, and uses an opaque GCLID read by Google. Manual UTM tagging is something you write yourself, works on any channel, and uses readable values read by GA4. Most teams use both together.
Does auto-tagging replace UTM parameters?
No. Auto-tagging only covers Google Ads clicks. Channels like email, organic social, and non-Google ads still need manual UTM parameters to be tracked correctly in GA4.
Is auto-tagging on by default?
Yes. Google enables auto-tagging by default for new Google Ads accounts and recommends keeping it on. You can confirm or change it under Admin, then Account settings, in Google Ads.
To tag the channels auto-tagging does not cover, build clean campaign links with the free Google Ads UTM builder at linkutm.