What Is Conversion Tracking | The Base of Measurement
Conversion tracking is the mechanism that records whether someone who clicked your ad went on to do something valuable to you. Without it, Google Ads only shows you click count — you know what you spent, not what you earned.
The setup itself is covered on the conversion tracking setup page; here I explain how the mechanism works.
How it works
When a user clicks the ad, a marker is left in their browser. When they later perform the action counted as a conversion — submitting a form, buying, calling — that action is matched to the marker and reported back to Google Ads.
This is how you see which campaign, which ad and which search produced the result. Every smart bidding strategy feeds on this exact signal: it’s how the algorithm learns what works.
What should count as a conversion
Only the action that genuinely earns money, or comes closest to it. Form submission, phone call, WhatsApp message, purchase, quote request.
Page views, scrolls or time on site are not conversions. Marked as such, the count looks high but the algorithm starts hunting the wrong person — drifting toward an audience that browses easily but never buys.
Why it breaks silently
The most dangerous trait of conversion tracking is that it doesn’t throw an error when it breaks. Campaigns keep running, no warning appears in the interface, and only the conversion count falls.
The most common causes: the tag getting wiped after a theme or plugin update, the thank-you page redirect being removed, measurement not carrying over during a site rebuild. This drop usually gets mistaken for a performance problem, leading to wrong decisions.
That’s why regular verification is necessary. It’s the single most common issue I find in accounts I take over.
Double counting
The second common problem is the same action being counted twice. When a conversion imported from GA4 and Google Ads’ own tag are both set as primary at once, a single sale shows as two conversions.
The result is a picture that looks better than reality, and an algorithm learning from inflated data. I cover the detail on the GA4 link page.
Want help? I can test your existing measurement and confirm whether it’s actually working. You can reach me from the contact page.
Frequently Asked Questions
Why does my conversion count differ from my real sales count?
Some difference is normal — ad blockers, consent refusals and attribution differences all play a part. If the gap keeps widening, there’s a structural problem.
Have cookie restrictions ended measurement?
Not ended, but weakened. Enhanced conversions and modelling recover part of the lost data.
How do I measure a customer who calls?
That needs a separate setup — a call extension, a forwarding number, or number-tap tracking. Covered on the call conversion tracking page.