How to Set IP Address as a Custom Dimension in GA4

Table of Contents

Updated: December 19, 2025

Warning: Google Analytics 4 is not allowed to send PII information. If you want to send it, please encrypt it first. This article is for demonstration purposes only. This blog does not collect user IP.

As is well known, Google Analytics 4 does not expose a native IP address field.

However, in practice, many users still want to associate IP-related information with GA4 data for analytical or technical purposes.

This can be achieved indirectly by using JavaScript, first-party cookies, and Google Tag Manager (GTM)—while ensuring the data is encrypted and handled carefully.

Solution Overview

The overall approach is as follows:

On every page load, use JavaScript to call a third-party API to retrieve the user’s IP address.
Encrypt the IP address.
Store the encrypted value in a first-party cookie.
Read the cookie value in GTM.
Send it to GA4 as a user-scoped custom dimension.

Setup Process

Step 1 : Custom HTML Tag

In GTM, click 「Tags」——「New」—— 「Choose a tag type to begin setup…」 ——「Custom HTML」 and then configure the tag as follows:

Code：

Code

<script type="application/javascript">
   $.get("https://ipinfo.io", function(response) {
     var cookieName= "ipnum";
     var cookieName2= "ipcity";
    var ipnumber  =response.ip;
     var ipcity  =response.city;
    var cookiePath  = "/";
    var expirationTime = 172800*15;                           
    expirationTime = expirationTime * 1000;
    var date = new Date();
    var dateTimeNow = date.getTime();
    date.setTime(dateTimeNow + expirationTime);
    var expirationTime = date.toUTCString();
    document.cookie = cookieName+"="+ipnumber+"; expires="+expirationTime+"; path="+cookiePath;
      document.cookie = cookieName2+"="+ipcity+"; expires="+expirationTime+"; path="+cookiePath;
        }, "json")
</script>

Set the Tag firing priority to 9999 to ensure this tag runs before the GA4 Page View tag, allowing the IP value to be available in time.