Where the sessions behind your cookie banner go

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The sessions behind your cookie banner still happen. The visitor lands, browses and buys; what changes is what your tags may store and send. Under Basic Consent Mode those visits send Google nothing. Under Advanced, Google tags send cookieless pings, and Google may model some of the missing conversions once your account meets its thresholds.

How many sessions sit behind the banner?

No single figure holds across sites. The share depends on where your visitors are, what kind of site it is, how the banner is designed and whether rejecting is as easy as accepting. The number that matters is your own. Your consent tool reports its accept and reject rates, and they are worth reading by country and by device before you change a campaign or a budget.

Those sessions do not disappear from your business. They disappear from your dashboards. The visitor still lands, browses and buys, but GA4 does not count them as users, Google Ads cannot tie the sale to the click, and ROAS reads lower than it is. The usual result is budget moving away from campaigns that were working.

What does a refusal remove from your reports?

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.

What does Consent Mode send instead?

Consent Mode is Google's way of telling its tags what the visitor chose, and it comes in two implementations. Google's consent mode overview sets out the difference. In Basic, Google tags stay blocked until the visitor interacts with the banner, so a refusal sends nothing. In Advanced, the tags load with every signal set to denied and send cookieless pings: no cookies and no client identifier, only the fact that a page view or a conversion happened.

The difference shows up in modelling. Google describes Basic as supporting a general model and Advanced an advertiser specific one, built from your own site's pings. Whether Advanced suits you is partly a legal question, because some teams are advised to send nothing before consent. Our post on basic vs advanced Consent Mode shows how to tell which one you are running.

When does Google model the missing conversions?

Only above a threshold, and the result is an estimate rather than conversions anyone observed. Google Ads needs 700 ad clicks over 7 days per country and domain grouping before consent mode modelling starts. Modelled conversions then appear in the ordinary Conversions column.

GA4 has its own prerequisites for behavioural modelling. It needs at least 1,000 events a day with analytics storage denied for 7 days, and at least 1,000 daily users with it granted on 7 of the previous 28 days. Google adds that meeting them does not guarantee eligibility.

Below those thresholds, Advanced still sends the pings and you get no modelled data. That is worth knowing before anyone plans a budget around modelled numbers. We cover the timing in what consent modelling is and when it starts.

What should you check on your own site?

Three checks tell you most of the story.

1. Check how consent reaches Google

   Does your banner pass consent state to Google through Consent Mode v2, or does it simply block tags? Blocking alone leaves Google nothing to model from.

2. Confirm the defaults fire first

   The four consent signals should be set before any Google tag loads. A tag that fires before the defaults exist misbehaves in exactly the browsers you cannot see. If you want the report level view of this, we went through exactly what happens to your GA4 data when a visitor rejects in a separate post.

3. Watch a rejection in the network tab

   When a visitor declines, do your tags fall silent completely, or do they keep sending the anonymous pings that conversion modelling depends on?

Velo sets the Consent Mode defaults as soon as its snippet runs, so placing it above your tags means they read a denied state first. It sends the update when the visitor chooses and records each choice with a timestamp. Whether Google models anything is still Google's decision, made against the thresholds above. See how it works.