Conversion Linker Explained: What It Is & Why Google Ads Needs It

The Conversion Linker is one of the most important, and most misunderstood, tags in Google Tag Manager. It has no dashboard, sends no data to any account, and most people never think about it. But without it, your Google Ads conversion tracking quietly breaks. Here is exactly what it does and why every Google Ads advertiser needs it.

What is the Conversion Linker?

The Conversion Linker is a built-in Google Tag Manager tag type (internally __gclidw). It is a utility tag: rather than tracking a pageview or a purchase, its only job is to capture and preserve the information Google needs to connect an ad click to a later conversion.

Because it does not report to any account, it has no tracking ID, which is completely normal. In Tag Explorer you will see it listed with no ID number, and that is correct.

What it actually does

When someone clicks a Google Ad, Google appends click identifiers to your landing-page URL:

• gclid, the Google Click ID (standard web clicks)
• gbraid / wbraid, click IDs used for iOS and in-app traffic

The Conversion Linker reads those identifiers from the URL and stores them in first-party cookies on your own domain (_gcl_aw, _gcl_dc and similar). Later, when the visitor converts, buys a ticket, submits a form, makes a purchase, your Google Ads Conversion and Floodlight tags read those cookies and attribute the conversion back to the original ad click.

Why it matters more than ever

Web browsers have aggressively restricted third-party cookies. Safari’s Intelligent Tracking Prevention (ITP) and similar measures mean ad platforms can no longer rely on cross-site cookies to remember a click. The Conversion Linker sidesteps this by writing first-party cookies, which browsers trust far longer. Google now effectively requires the Conversion Linker for accurate Google Ads conversion measurement, without it, conversions go unattributed and your campaign optimisation suffers.

How it should be set up

Best practice is to fire the Conversion Linker on every page, as early as possible, usually on the Initialization, All Pages trigger, so the click ID is captured the moment a visitor lands. It belongs alongside your other Google tags:

• Google Tag (gtag.js)
• Google Ads Conversion Tracking
• Floodlight (if you use Campaign Manager 360 / DV360)

How to check yours is working

The fastest way is to scan your site with our free Tag Explorer tool. If the Conversion Linker is published in your container, it will appear nested under your GTM container. To confirm it is actually firing, use GTM’s Preview mode and check that it shows under “Tags Fired” on page load.

Common questions

Why does it have no ID? Because it is plumbing, it manages cookies rather than reporting to an account. No ID is expected.

Do I need it if I only use GA4? It is specifically for Google Ads / Floodlight attribution. If you run Google Ads, yes. If you only use GA4 with no ads, it is not required.

Is it a duplicate or a problem? No, a single Conversion Linker firing on all pages is exactly right. Leave it in place.

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Part of the Shipwreck Studio Tag Guide. Scan any page with Tag Explorer to see its full tag tree.