Enhanced Client ID (ecid) in Google Analytics 4

Update time: January 5, 2025

This article introduces Enhanced Client ID in GA4

What is Enhanced Client ID？

Enhanced Client ID, abbreviated as ecid. You can see it in the preview of GTM:

Enhanced Client ID is generated based on the Client ID and other identifiers (such as User ID, device information, etc.). It adds additional information to better identify users in multiple environments.

It is used to improve and enhance the tracking of user identities. Its main function is to help improve the accuracy of user tracking across devices and platforms.

Note: Enhanced Client ID is session-level. When a new session is opened, a new Enhanced Client ID will be generated.

Enhanced Client ID Format

The Enhanced Client ID is a string of numbers (0 in the example, which means it is not generated) stored in _ga_<container ID>. The structure is as follows:

How to enable Enhanced Client ID

There are two situations that will generate Enhanced Client ID:

• One way is to turn on 「User-ID and user-provided data collection」， In GA4, click 「Admin」——  「Property Settings」—— -「Data collection and modification」——「Data collection」and check 「User-ID and user-provided data collection」.
• One is to use GTM server-side deployment

You can see it in Cookie _ga_<container ID>:

Client ID VS  Enhanced Client ID

Read More：

• In-depth Understanding Session in Google Analytics 4
• Explanation of Cookie Values ​​Used by Google Analytics 4
• Learn more about Client ID in GA4 (CST & SST)