Consent Mode conversion modelling: what it estimates and what it needs
This page is technical, not legal. Whether and how you ask for consent is a question for your counsel. Where it sits in the stack is on the ecommerce marketing technology stack page.
What does it do?
Google's Tag Manager help describes two modes1:
- Basic. Tags do not load until the visitor answers the banner. If they decline, no data goes to Google, not even the consent status. Conversion modelling in Google Ads then uses a general model.
- Advanced. Tags load when the page opens. While consent is denied, they send cookieless pings. Google says this enables an advertiser-specific model.
In GA4, behavioural modelling uses that signal to estimate behaviour from users who did not consent. Google's Analytics help sets its conditions. For web pages, it needs tags that load before the consent banner appears, which is the advanced set-up2. It also needs volume: at least 1,000 events a day with analytics storage denied for at least 7 days, and at least 1,000 daily users with it granted for at least 7 of the previous 28 days2. Google adds that meeting these thresholds does not guarantee eligibility2.
Some limits from the same page. Modelled data is not available in data exports such as BigQuery, and in reports event counts such as page_view are not modelled2.
Why do e-commerce brands care?
Because it touches the numbers you trust.
For end users in the EEA, Google's EU user consent policy page says advertisers using personalisation, remarketing and measurement must collect consent and share consent signals with Google3. If the signals are wrong, conversions can vanish from your reports. One trade-press report describes a single advertiser whose banner collected choices but did not pass them to Google's tags, after which Google Ads conversions fell sharply4. One case is not a rate, but it shows what a broken connection can do.
Modelling then fills part of the gap, if you qualify.
How do we implement it?
Check the banner connection
Test what fires before and after consent. A banner can look right and still pass no signals to your tags.
Choose the mode
GA4 behavioural modelling needs tags that load before the banner, which is the advanced set-up. Decide basic or advanced knowing that, with your counsel.
Check the thresholds
Check your numbers against Google's conditions before counting on modelling. Smaller brands may never reach them.
Label modelled figures
Keep modelled numbers apart from counted ones. Someone has to know which is which.
When should you not rely on it?
Do not rely on modelling when:
In those cases, the useful step is to check the setup. You can start with our free tracking audit.
What does it cost in effort?
No money figures here. The effort sits in a few places:
- Consent banner. It must pass choices to tags correctly.
- Tag set-up. Tags have to respect the signals. This is easy to get wrong.
- Testing. Check what fires before and after consent.
- Reading the output. Someone has to know which figures are counted and which are modelled.
Your first-party data is the other side. Orders and customer records still exist whatever the banner says. Enhanced conversions and server-side tracking are separate tools, and neither replaces consent. Your counsel decides what is allowed.
Pitfalls
A banner not connected to tags
The banner looks right but the signals never arrive4.
Thinking modelling is data
It is an estimate of what was not observed.
Missing the thresholds
Modelling needs enough volume2.
Looking for modelled data in BigQuery
It is not in the export2.
Assuming it is optional in the EEA
Google's policy asks for consent signals there3. Your counsel decides what applies to you.
Reading a drop as a market change
Check consent signals first.
Our take: Core and Selective
Our rating has two parts. This is our view, not a market fact.
Consent Mode: Core. For EEA traffic, Google's policy asks advertisers to share consent signals3, and the set-up is documented1. A brand running Google ads in Europe should know where it stands.
GA4 modelling: Selective. It only works on an advanced implementation and above the volume thresholds2. Smaller brands may never reach them.
Our view: treat modelled numbers as estimates and keep them separate from what you counted. Do not present them as recovered visitors.
FAQ
What is consent mode conversion modelling?
Google estimates conversions it cannot observe when users decline consent; advanced mode gives an advertiser-specific model, basic mode a general one1.
Does modelling recover lost data?
No. It estimates. It does not bring back the data of people who declined.
What does GA4 need for behavioural modelling?
On the web, tags that load before the consent banner, plus volume: at least 1,000 events a day with analytics storage denied for 7 days, and at least 1,000 consenting daily users on 7 of the previous 28 days2.
Does basic consent mode support modelling?
In Google Ads, yes, with a general model; advanced mode gives an advertiser-specific one1. GA4 behavioural modelling needs tags that load before the banner2. The trade-offs are in Consent Mode basic vs advanced.
Are modelled conversions in my BigQuery export?
No. Google lists data export, such as BigQuery, among the features without modelled data2.
Do I need Consent Mode in the EEA?
Google's policy sets advertiser duties for EEA traffic3. Your counsel decides what applies to you.
Sources
Let’s find what’s actually working.
Next step. Want a view on your consent and tracking set-up? Talk to us about your budget decision. Or read about our Analytics & tracking service.