This article is about Google Analytics 4 properties. Refer to the Universal Analytics section if you're still using a Universal Analytics property, which will stop processing data on July 1, 2023 (October 1, 2023 for Analytics 360 properties).

[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 3 different types of identifiers to stitch them together into a single unified cross-device user journey:

  • User ID
  • Google signals
  • Device ID

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.

Google signals

Google signals is data from users who are signed in to Google. When Google signals data is available, Analytics associates event data it collects from users with the Google accounts of signed-in users who have consented to sharing this information.

Learn how to activate Google signals.


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.

How Analytics determines the reporting identity

Your property's reporting identity determines how Analytics associates events with users. In GA4 properties, data is processed using all available identity spaces. When a user triggers an event on your site or app, Analytics first checks to see if you've provided a signed-in user ID. If there isn't a user ID, Analytics tries to differentiate users based on Google signals data. If Google signals data isn't available, Analytics relies on device ID to differentiate users.

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.

Set the reporting identity for your property

  1. Sign in to Google Analytics.
  2. Click Admin, and navigate to the property you want to edit.
  3. In the Property column, click Reporting Identity.
  4. Select the reporting identity you want to use.
  5. Click Save.

Reporting identity options

  • By User-ID, Google signals, then device: Uses the user ID if it is collected. If no user ID is collected, then Analytics uses information from Google signals if that is available. If neither User-ID nor Google-signals information is available, then Analytics uses the device ID.

    Note: To use this option, you must activate Google signals. In addition, your property must have enough activity from signed-in users to adequately anonymize their identity. If there isn't enough data from Google signals, then you'll only see the next two reporting identity options.

    Note: When you activate Google signals, Analytics collects demographics and interests data when it is available. As a consequence, your reports are subject to data thresholds.

    • By User-ID and device: Available if you have not activated Google signals. Uses the user ID if it is collected. If no user ID is collected, then Analytics uses the device ID.
    • By device: Uses only the device ID and ignores any user IDs that are collected.
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.
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