Log in to your Google Analytics Account and perform the following tasks:
- In Google Analytics, click Admin (lower left).
- In the Account column, make sure that your desired account is selected. (If you only have one Google Analytics account, it's already selected.)
- In the Property column, select the GA4 property that currently collects data for your website.
- In the Property column, click Data Streams. It's the first option in the Property column.
- Select your domain from the list of data streams.
- You will find your MEASUREMENT ID next to STREAM ID.