What is gclid, and why does Vibel need it?

gclid is the click id Google Ads stamps onto your landing page URL when someone clicks a Google ad. It is how a later Shopify order gets credited back to that ad, and it is usually missing for a reason you can find and fix.

The short answer

gclid (Google click id) is a parameter Google Ads adds to the end of your landing page URL the moment someone clicks a Google ad: something like ?gclid=Cj0KCQiA... following your normal URL.

It exists so the click and the eventual conversion can be tied together. Without it, an order that genuinely came from a Google ad looks identical to one that came from anywhere else, because nothing about the order itself says which ad, if any, led to it.

Vibel reads this parameter off the landing session and carries it through to the order. When it is present, Vibel can show that order as Google-attributed. When it is not, the order is not wrongly blamed on another channel, it is shown as not measured instead - see the companion page on what that means.

Auto-tagging: where gclid actually comes from

You do not write gclid into your ads. Google Ads appends it automatically through a setting called auto-tagging, which is on by default for new accounts and lives under Account settings, Auto-tagging.

With auto-tagging on, every ad's landing page URL gets ?gclid=... added at click time, regardless of what URL you entered when building the ad. This is also what lets Google Ads itself report conversions without you doing anything extra.

Good to know

Auto-tagging can be switched off, usually by accident during an account setup or an agency handover. An account with it off sends clicks with no gclid at all, and every single Google Ads conversion becomes unmeasurable, not just a share of them.

What breaks it even when auto-tagging is on

Auto-tagging being on is necessary but not sufficient. A few setups strip or overwrite the parameter after Google Ads adds it:

1A tracking template or Final URL suffix that rebuilds the URL instead of appending to it. The safe pattern keeps the original query string intact (Google's own {lpurl}?{ignore} style suffix); a hand-built template that does not reference the existing URL can drop gclid entirely.
2A redirect chain between the ad and your actual landing page. Each hop is a chance for a URL parameter to be dropped, especially through a link shortener or a redirect rule that does not explicitly forward the query string.
3A landing page that redirects client-side (JavaScript) to a clean URL for appearance, discarding gclid before anything reads it.
4Server or CDN rules that strip unknown query parameters for caching reasons, which has nothing to do with ads and everything to do with how the page is served.

How to check it

This takes about two minutes and needs no tool beyond your browser.

1In Google Ads, open Account settings and confirm Auto-tagging is on.
2Use the ad preview and diagnosis tool, or click a live ad yourself from an incognito window, and look at the resulting landing page URL in the address bar.
3Confirm it carries ?gclid=... (it may be combined with other parameters after an & sign, that is normal).
4If you use a tracking template or Final URL suffix, repeat the check specifically for that campaign, since a template can be set per account, per campaign or per ad, and only one broken level is enough to lose it there.

Why this matters more than it looks

A missing gclid does not make Google Ads report fewer conversions in its own interface, because Google's own tracking can still work even when gclid never reaches your store. It specifically breaks the comparison between what Google claims and what Shopify actually sold, since that comparison needs the same click id on both sides.

This is the gap Vibel's tracking checks are built to catch: a store can have perfectly good Google Ads reporting and still show a growing not measured share in Vibel, because the two are reading different things.

Meta Events Manager settings: what to check on a Shopify store

What does "not measured" mean in Vibel's attribution? →