Where 34% of your sessions actually go
On a typical site, roughly a third of sessions never make it into your reports. The visitors are real, the clicks are real, the purchases are real. The measurement is what goes missing. Here is where that traffic goes, and what you can do about it.
The gap nobody budgets for
Across the client sites our team has measured, about 34% of sessions sit behind the consent banner: visitors who reject, ignore the banner, or leave before deciding. That figure is a measured baseline across Amplio Data implementations, not a universal constant — your mix of regions, devices and traffic sources moves it up or down. But on almost every site we audit, the gap is far larger than the team assumed.
Those sessions do not disappear from your business. They disappear from your dashboards. The visitor still lands, browses and buys. GA4 simply never hears about it, Google Ads cannot attribute it, and your ROAS looks worse than it is. The most common consequence is quiet and expensive: budgets shift away from campaigns that were actually working.
What consent actually blocks
When a visitor declines analytics or advertising storage, tags that depend on cookies stop setting and reading them. Without a cookie there is no stable identifier, so sessions fragment, conversions detach from the clicks that caused them, and remarketing lists stop growing. A banner that fires tags too early has the opposite problem: you get the data and a compliance risk along with it.
How Consent Mode v2 changes the picture
Consent Mode v2 is Google's protocol for telling its tags what the visitor chose. In its advanced implementation, tags stay loaded and send cookieless pings when consent is denied: no identifiers, no profiles, just anonymous signals that a conversion event happened. Google then uses those pings to model conversions — statistically recovering the outcomes it can no longer observe directly and feeding them back into Google Ads and GA4.
Modelling does not return every lost conversion, and Google applies eligibility thresholds before it activates. But on sites with meaningful traffic it closes a large share of the gap between what happened and what got measured, which is the difference between cutting a campaign and scaling it.
What to check on your own site
Three questions tell you most of the story. Does your banner pass consent state to Google through Consent Mode v2, or does it simply block tags? Are the four consent signals set before any Google tag fires? And when a visitor declines, do your tags fall silent completely, or do they keep sending the anonymous pings modelling depends on?
If you are not sure, that is exactly what Velo is built to handle: the banner, the consent signals and the recovery path, wired correctly from day one.