How to Simultaneously Utilize Google Analytics 4 and Universal Analytics

[Harper]

You’re on the right track and the code looks almost correct, but there’s a slight mistake. You don’t need two separate script tags for the Google Tag Manager, you can load multiple tags through a single script. You should remove one of them, ideally the UA one. Instead, combine the id references in the gtag.js URL and gtag(‘config’) commands. Like this:

<script async src="https://www.googletagmanager.com/gtag/js?id=G-xxxxxxx"></script>
<script>
        window.dataLayer = window.dataLayer || [];

        function gtag() {
            dataLayer.push(arguments);
        }

        gtag('js', new Date());

        gtag('config', 'G-xxxxxxx', {'debug_mode': true});
        gtag('config', 'UA-xxxxxxxx-x', {'debug_mode': true});

</script>

Now both GA4 and UA tracking will be linked, with the gtag.js loading only once. Remember to replace ‘G-xxxxxxx’ with your GA4 id and ‘UA-xxxxxxxx-x’ with your UA id. This will allow you to have both UA and GA4 tracking on your webpage at the same time.

[John]

The idea of running Universal Analytics (UA) and Google Analytics 4 (GA4) simultaneously on the same webpage is a common approach when transitioning from UA to GA4, as it allows you to have both versions running at the same time. The script you presented does reflect this approach. However, you don’t need to include the ‘gtag.js’ script twice for both UA and GA4. You only need to include it once, then specify both tracking IDs (GA4 and UA) in the ‘config’ calls within the script. ‘Debug_mode’ is also an optional parameter. If it’s set as true, it will produce verbose debug information to the console; remove it or set as false in a live environment.