[GA4] Reporting identity

Learn how Google Analytics measures users across devices and platforms.

An individual customer often interacts with your business using different devices and platforms. For example, someone might browse your products on a Pixel tablet at breakfast, do more research using a browser on their work computer at lunch, then make a purchase on their iPhone after dinner. While each of these activities is a separate session, Google Analytics 4 can use the following methods to unify them into a single cross-device user journey:

  • User-ID
  • User-provided data
  • Device ID
  • Modeling

Analytics creates a single user journey from all the data associated with the same identity. Because these identity spaces are used in all reports, they allow you to de-duplicate users and tell a more unified, holistic story about their relationships with your business.

Identity spaces

Collectively, the identifiers listed above are called identity spaces, and the identity space(s) used by your Analytics property is called its reporting identity.


If you create your own persistent IDs for signed-in users, you can use these IDs to measure user journeys across devices. To use this identity space, you must consistently assign IDs to your users and include the IDs along with the data you send to Analytics. User-ID is the most accurate identity space, because it uses data you collect to identify your users.

Learn how to implement User-ID.

User-provided data

If you collect user-provided data (hashed, consented personal data) without user ID with the data you send to Google Analytics, user-provided data can serve as the identifier in the user-ID identity space. When this occurs, for each session, Analytics will prioritize the user-provided data in the following order: email, phone number, name and address.

Learn more about user-provided data collection.


Analytics can also use device ID as an identity space. On websites, the device ID gets its value from the client ID. On apps, the device ID is the app-instance ID.


When users decline Analytics identifiers like cookies, behavioral data for those users is unavailable. Analytics fills this gap by using the data of similar users who do accept cookies from the same property to model the behavior of the users who decline cookies. Learn more

How Analytics determines the reporting identity

Analytics determines your reporting identity based on which identity spaces you choose to collect and which ones you make available via the following options.

Reporting identity options

  • Blended: By User-ID, device ID, then modeling. Uses the user ID if it is collected. If User-ID information is not available, then Analytics uses the device ID. If no identifier is available, Analytics uses modeling.
  • Observed: By User-ID, then device ID. Uses the user ID if it is collected. If User-ID information is not available, then Analytics uses the device ID.
  • Device based: Uses only the device ID and ignores all other IDs that are collected.

To get the full benefit of the first two options, you need to collect user IDs. In addition, your property must have enough activity from signed-in users to adequately obfuscate their identity. As a consequence your reports are subject to data thresholds.

Note: The option you choose does not affect data collection or processing. You can switch between the options at any time without making any permanent impact on data.

Set the reporting identity for your property

  1. In Admin, under Data display, click Reporting identity.
    Note: The previous link opens to the last Analytics property you accessed. You can change the property using the property selector. You must be an Editor or above at the account level to set the reporting identity for your property.
  2. Select the reporting identity you want to use.
  3. Click Save.

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