What is the _gcl_gs cookie?
_gcl_gs is an HTTP cookie belonging to the "Google Click Identifier" (gcl) cookie family used by Google Ads and Google's tagging tools (Google Tag Manager, gtag.js, Google Ads Conversion Tracking). It is set on the visited website's domain, typically by the Google Ads conversion tracking script or Google Tag Manager installed on the page.
It generally appears when a visitor arrives at the site via a click on a Google Ads advertisement (a link containing the gclid parameter) or when the site has an active Google conversion tracking tag. It is not set directly by Google.com, but by the script installed by the site owner.
What data it stores
_gcl_gs generally stores state information related to the presence and configuration of Google Click Identifier tracking for that session (for example, indicators about whether conversion data transmission is enabled), rather than the actual click identifier itself. The exact value format is generated and interpreted by Google's scripts and can vary; it is not publicly documented in detail by Google.
Data collected through this mechanism is sent to Google Ads servers, where it is associated with the campaign, keyword, or ad that generated the click, for conversion reporting purposes.
What it is used for
Its main purpose is to support conversion measurement for Google Ads campaigns: it allows a website to report back to Google when a visitor who arrived via an ad completed a desired action (purchase, form submission, call, etc.).
For the site owner, this data feeds Google Ads conversion reports, enabling optimization of ad spend and bidding strategy. For Google, it contributes to improving automated bidding algorithms (Smart Bidding).
Does it require consent?
CookieFix classifies _gcl_gs as a marketing/advertising cookie, since it is used to track users for advertising conversion measurement purposes. It is not strictly necessary for the website to function.
- Under the GDPR and the ePrivacy Directive (2002/58/EC, transposed in Romania via Law 506/2004), prior consent from the visitor is required before this cookie is set.
- Site owners must list it in their cookie policy under the "marketing" category and ensure the Google Ads Conversion Tracking / Google Tag Manager script only fires after the visitor has explicitly given consent.
How to block or delete _gcl_gs
A visitor can delete or block _gcl_gs manually from browser settings (Chrome, Firefox, Edge, Safari – site cookie management section), or use ad/tracker-blocking extensions. Deleting the cookie does not affect the website's core functionality.
For site owners, blocking should happen at the consent layer: a CMP such as CookieFix can automatically block the Google Ads/Google Tag Manager script that sets _gcl_gs until the visitor consents to the marketing category, preventing the cookie from being set without a legal basis.
Frequently asked questions
Yes, as a marketing/tracking cookie used by Google Ads, it requires the visitor's prior consent under the GDPR and ePrivacy rules.
It typically has a duration of around 90 days from being set, after which it expires automatically from the browser.
Both belong to the Google Click Identifier cookie family related to Google Ads, playing complementary roles in click and conversion tracking; the internal technical details aren't fully published by Google.
The website continues to function normally, but Google Ads may report ad-driven conversions for that visitor less accurately.