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Conversion Linker

Conversion Linker is a Google Tag Manager tag that stores ad click details in the shop's own cookies, so a later purchase can be tied back to that click.

How it works

After an ad click, its details sit in the landing page address. By the thank-you page, they are gone. The Conversion Linker tag in Google Tag Manager reads them on the landing page. It stores them in first-party cookies on the shop’s domain (_gcl_aw, _gcl_gs and others) and in local storage.

When a purchase fires the Google Ads conversion tag, that tag reads the stored details and ties the order to the click. So the linker has to fire wherever a visitor may land: Google recommends the All Pages trigger. A container that loads a Google tag on every page does not need the linker.

Without Tag Manager, the Google tag does the same job. Google warns that turning this off (conversion_linker: false) makes measurement less accurate.

Where you see it

  • Google Tag Manager: Tags → New → Tag Configuration → Conversion Linker, with the option “Enable linking across domains”.
  • Google Ads conversion tags in Tag Manager: “Enable Conversion Linking”, on by default.
  • Checking it: Preview mode and Google Tag Assistant show whether the tag fires on landing pages. See how to check that it really works.

Example

Example store, not client data.

The tableware shop takes payment on a separate checkout domain, which cannot read the shop’s cookies. With “Enable linking across domains” on, links to the checkout get a linker parameter. A linker tag on the checkout domain stores the click details in its own cookie.

Not to be confused with

  • Auto-tagging — the Google Ads setting that adds the click ID to the URL. Without it there is no click ID to store.
  • GCLID — the click ID itself. The linker keeps it after the visitor leaves the landing page.

Right and wrong readings

  • Wrong: “The linker only needs to fire on the thank-you page.” Right: it has to fire where the visitor lands. By the thank-you page, the click details are gone.
  • Wrong: “Our Google Ads conversion tag loads a Google tag itself, so we need no linker.” Right: that Google tag loads only where the conversion tag fires: the thank-you page. Only a Google tag on every page makes the linker unnecessary.

Sources

  • Conversion linker (Tag Manager Help) — what the tag stores, the All Pages trigger, the Google tag exemption, cross-domain linking. Checked 2 October 2026.
  • How Google Ads tracks website conversions (Google Ads Help) — the Google tag’s first-party cookies and the opt-out. Checked 2 October 2026.