What is the _gcl_dc cookie?
_gcl_dc is a first-party HTTP cookie generated by Google Ads scripts (Google Click Identifier – display variant) when a site uses conversion linking or conversion tracking for display/remarketing campaigns. It is the counterpart of _gcl_aw, but dedicated to clicks originating from the Google Display Network rather than Search.
It appears on a site once the site owner has installed the Google global site tag (gtag.js) or Google Tag Manager with a Google Ads conversion tag, and a visitor has arrived via an ad shown on the Google Display Network.
What data it stores
The cookie stores a unique identifier tied to the ad click (an encrypted alphanumeric string, similar in format to the GCLID value used in the gclid URL parameter), along with a timestamp of the click. It does not contain a name, email, or other directly identifying data, but it is still considered personal data because it links online behavior to a specific user/device.
Its value is read by the Google Ads scripts installed on the site and sent to Google's servers (google.com/ads) to attribute conversions to the corresponding campaign and ad.
What it is used for
Its main purpose is conversion attribution: it lets Google Ads determine whether a visitor who clicked a display ad later completed a desired action on the site (purchase, form submission, sign-up). For the site owner, this data feeds campaign performance reports and automated bid optimization.
Without this cookie, Google Ads cannot connect a user's later visits to a specific ad click, which reduces the accuracy of ROI measurement for display campaigns.
Does it require consent?
Under CookieFix's classification, _gcl_dc is a marketing/advertising cookie, not strictly necessary. Under the GDPR (Regulation 2016/679) and the ePrivacy Directive (transposed in Romania via Law 506/2004), placing it requires the visitor's prior, explicit, and informed consent, obtained through a consent banner.
- The site owner must declare this cookie in the cookie policy, including provider, purpose, and duration.
- The script that sets the cookie must be technically blocked until consent is given, not merely hidden from view.
- Refusing consent must not affect the site's core functionality.
How to block or delete _gcl_dc
A visitor can delete or block this cookie from browser settings (Chrome, Firefox, Edge, Safari – cookie/site data management section), or use ad-tracking blocker extensions. Turning off ad personalization in a Google account also reduces this type of data collection.
For site owners, the most effective approach is blocking Google Ads scripts automatically before consent is given, using a CMP like CookieFix, which prevents conversion tags from loading until the visitor explicitly selects the "marketing" category in the banner.
Frequently asked questions
It's a tracking cookie set by Google Ads to measure conversions generated by clicks on ads from the Google Display Network.
Typically 90 days from the last ad click, after which it expires automatically from the browser.
No, it contains no malicious code; it's an advertising performance measurement cookie, but it does involve tracking user behavior, which is why consent is required.
Yes, as a marketing cookie it requires the visitor's prior consent before being set, and the site must disclose it in its cookie policy.