Your CPL is lying — and your agency probably doesn't know it.
“Our cost-per-lead is €23.” Nice number. We always ask the same thing back: €23 based on what? Nine times out of ten, we get silence.
That’s because “conversions” come from two different places, and they don’t count the same thing.
Google Ads conversions are the actions you flagged as a conversion inside Google Ads, credited to the click that caused them, with an attribution window and often a bit of modelling on top.
GA4 events are everything GA4 records: pageviews, scrolls, form starts, and yes, your lead event too. A GA4 conversion (key event) is not the same as an Ads conversion. Counted at a different point, attributed differently, defined differently.
Mix the two up, spend from Google Ads divided by events from GA4, and out comes a CPL that means nothing. Sometimes too good, sometimes too bad. Never the number you think it is.
The honest maths. Monthly CPL is Google Ads spend divided by Google Ads conversion actions. One source, one window, one count. Not divided by GA4 events.
It sounds like splitting hairs, until you remember you’re making decisions on this. Raising budget, pausing a campaign, keeping an agency or firing one, all on a number stitched together from two different systems.
What we do ourselves is boring: one CPL definition, written down, calculated the same way every month. Boring is exactly the point. You can trust it month after month.
Want to know which number your report is actually showing you? That’s the first thing we dig into in a free audit.