How to track webinar attendance to purchase for Google Ads

Architecture

The exact event sequence

Five stages. Two breaks, not one: the identifier is lost at registration because the form is hosted elsewhere, and then lost again between the webinar and the purchase because days pass and the device changes. The identifier has to survive all of them.

1. Step 1

   Ad click

   The identifier arrives on the registration page. Capture it here — the webinar platform will not.

2. Step 2

   Registration

   On a webinar platform's hosted form in most cases, which means the identifier has to be pushed in as a field rather than read from the page.

3. Step 3

   Attendance

   Registration-to-attendance runs between a third and a half for cold traffic. It is the single largest drop in this funnel.

4. Step 4

   Replay watched

   A real stage. Replay buyers are a meaningful share of revenue and are invisible if you only count live attendance.

5. Step 5

   Purchase

   Days later, from an email, on a different device. This is the event worth optimizing toward and the hardest one to connect.

Diagnostic sequence

What's specific to Google Ads

The funnel logic above is the same wherever you advertise. These are the parts that change because it's Google Ads.

1. 1

   Click identifier: gclid, gbraid and wbraid

   Three parameters, not one. gclid is the long-standing identifier; gbraid and wbraid arrive on iOS traffic where privacy constraints prevent the usual one. Capture code that names only gclid loses a growing share, silently, and the loss is invisible until you audit how many records carry an identifier.

2. 2

   Import mechanism: offline conversion import

   Uploaded against the click identifier, either through the Google Ads API or as a file. The upload is the easy part; what limits it is how many of your records carry an identifier at all. Verify the current column format against Google's own template — it has changed before.

3. 3

   Deduplication

   There's no shared event ID mechanism like Meta's. What matters instead is the counting setting on each conversion action — 'one' for lead-type conversions so a repeat submitter doesn't count three times, 'every' for ecommerce where a second purchase is a second sale. This is the single most common misconfiguration we find in Google Ads accounts.

4. 4

   Window and timing

   Google's offline import window is 90 days from the click. Anything older can't be matched, and rows outside it fail as unmatched without much explanation. Measure your median click-to-outcome time against that before designing anything.

5. 5

   The Google Ads gotcha

   A conversion action that stops receiving hits is flagged as inactive 30 days later — by which point a month of budget has already run against a missing signal. Check the last-received date on every action monthly; it takes two minutes and it's the cheapest monitoring available.

Source-of-truth validation

How to prove the chain works

One real journey, followed all the way, then a reconciliation. Neither on its own is enough.

• A live Google Ads ad clicked, and the identifier confirmed present on the landing URL.
• The same identifier confirmed on the order or opportunity that followed the webinar after a full real journey through every step.
• Purchase confirmed arriving at Google Ads, verified by the match rate on the upload, not the success message.
• Your billing or crm record, joined to the webinar attendance log reconciled against Google Ads per record over a fully closed window.
• The same reconciliation repeated 30 days later.

Straight talk

When this doesn't apply to you

Worth checking before you build anything, because two of these are common and both mean the work isn't worth doing.

• If your webinar is a support or onboarding session for existing customers, there is no acquisition funnel here and nothing to attribute.
• If you're running Performance Max exclusively and haven't separated your conversion actions, the import will work and the reporting won't tell you much. Worth sorting the account structure first.
• If your cycle from click to purchase regularly exceeds the import window, the final event can't drive bidding whatever you build. Optimize toward attendance of at least a defined watch duration instead and use the later data for budget decisions rather than for bidding.
• If almost none of your post-webinar orders carry a click identifier today, that's the whole project. Fix capture first — the import is the easy half and no tooling rescues a record with nothing to reference.