Consent Mode for Analytics vs Ads: Understanding the Difference

The Four Consent Mode Parameters Explained

Consent Mode v2 uses four parameters. analytics_storage controls whether GA4 can set analytics cookies and store identifiers for measurement and reporting.

ad_storage controls whether Google Ads and other advertising tags can set cookies for ad personalization, remarketing, and conversion attribution.

ad_user_data controls whether user data can be sent to Google for ads measurement and audience use. This is a Consent Mode v2 addition that was not in the original Consent Mode.

ad_personalization controls whether data can be used for personalized advertising, including remarketing.

The critical distinction for most implementations is that analytics_storage and ad_storage serve different purposes and should reflect different user consent choices.

A user who consents to "analytics cookies" in your CMP but declines "marketing cookies" should have analytics_storage granted and ad_storage denied.

Collapsing all four parameters to the same on/off toggle, as many simple Consent Mode implementations do, either over collects on the ads side or under collects on the analytics side.

How Each Parameter Affects GA4 Behaviour

With analytics_storage denied, GA4 does not set the _ga cookie, does not store user identifiers, and cannot perform cross session user recognition.

Events are still sent as cookieless pings that feed into conversion modeling.

Session counts, user counts, and other user based metrics are modeled for non consenting users rather than directly observed.

With ad_storage denied, Google Ads conversion tracking loses the ability to attribute conversions back to specific ad clicks via the GCLID cookie.

This limits Google Ads attribution quality and can reduce Smart Bidding signal quality.

With ad_user_data denied, audience lists cannot be populated with data from non consenting users. This affects remarketing audience sizes but does not affect analytics measurement.

Understanding which parameters affect which measurement systems helps you communicate the consent configuration trade offs to clients and stakeholders accurately.

Mapping Your CMP Categories to Consent Mode Parameters

The practical implementation challenge is mapping your CMP's consent categories, typically "necessary," "analytics," "marketing," and "preferences", to the four Consent Mode parameters in a way that accurately reflects what users are consenting to.

analytics_storage should grant when the user accepts analytics cookies. ad_storage and ad_user_data should grant when the user accepts marketing or advertising cookies.

ad_personalization should grant when the user explicitly consents to personalized advertising, some implementations treat this as the same as ad_storage, while others require a separate opt in.

Your CMP provider should have documentation on the recommended mapping for their specific implementation.

Auditing this mapping, comparing the Consent Mode parameter state in GA4 network requests against the consent categories the user actually selected, is the most reliable way to confirm the implementation is working correctly.