What is the _gcl_aw cookie?
_gcl_aw is an HTTP cookie tied to Google Ads' conversion tracking system (Google Click Identifier for Ads). It is set on the visited website's own domain (not by Google directly), usually through the Google Ads conversion tracking script, Google Tag (gtag.js), or Google Tag Manager.
It appears in the browser as soon as a visitor lands on the site via a click on a Google Ads ad containing a gclid parameter in the URL, or whenever the page loads an active Google Ads/Google Tag. In practice, any site running Google Ads campaigns with a conversion tag installed will set this cookie.
What data it stores
The value of _gcl_aw generally contains the ad click identifier (gclid) taken from the landing page URL, along with a timestamp. The exact value format varies and is not publicly documented in detail by Google.
The data is read by the Google Ads/gtag scripts loaded on the page and sent to Google's servers when an action defined as a conversion occurs (e.g., checkout completion, form submission). Essentially, the cookie links the ad click to the user's later action on the site.
What it is used for
Its main purpose is conversion attribution: Google Ads uses _gcl_aw to determine whether a visit originating from a paid campaign resulted in a valuable action (purchase, lead, sign-up). For the site owner, this cookie underlies the conversion reports in the Google Ads account and enables automated bid optimization based on actual results.
Without this cookie, Google Ads campaigns cannot correctly report conversions from the site, which affects both performance measurement and automated bidding strategies (Smart Bidding).
Does it require consent?
_gcl_aw is classified as a marketing/advertising cookie, used for tracking ad conversions. It is not strictly necessary for the site to function, so under GDPR and the ePrivacy Directive (transposed in Romania via Law 506/2004) it requires the visitor's prior consent before being set.
The site owner should: (1) declare the cookie in the cookie policy, including provider, purpose, and duration; (2) configure the Google Ads/Google Tag to fire only after consent (e.g., via Consent Mode or a CMP); (3) avoid setting it by default for EU/Romanian visitors without an active choice.
How to block or delete _gcl_aw
A visitor can delete or block _gcl_aw from browser settings (Chrome, Firefox, Edge, Safari – cookies and site data section), use private/incognito mode, or install tracking-script blocking extensions. Manual blocking only affects that visitor's own browser and doesn't prevent the cookie from being set for others.
- For the site owner, proper blocking means control at the site level, not just individual browser settings.
- A consent management platform (CMP) like CookieFix can automatically block the Google Ads/gtag script before the visitor makes a consent choice, so
_gcl_awis not set until the marketing category is accepted. - It's recommended that tag activation be technically conditioned on consent, not just declared in the policy.
Frequently asked questions
It's a marketing cookie set by Google Ads to track ad clicks and link visits from paid campaigns to conversions completed on the site.
The typical duration is 90 days from when it's set, after which it expires automatically unless renewed by a new ad click.
No. It's used exclusively for advertising and conversion measurement, so it requires visitor consent under GDPR and Romania's ePrivacy legislation.
You need to make the Google Ads/gtag firing conditional on visitor consent, for example by using a consent platform that blocks the script until the marketing category is accepted.