Gary Hainsworth

Should You Use Google Analytics, Global Site Tag or Google Tag Manager?

26th Apr 2021 Analytics 2 minutes to read

To the average user these might all be the same, but after a few headaches induced by these three, I can promise you they are different!

We often see conflicting, mis-firing and broken versions of Google Analytics (GA), Global Site Tag (Gtag), and Google Tag Manager (GTM) implemented on sites, but what do they do and which ones are preferred?


Google Analytics

This is the go-to for tracking visits and hits on your site. It is a web-based service that collects data from your visitors as they browse and interact with your site. There have been a few iterations including classic, universal, and GA4 – but for ease we’ll just call these Google Analytics.

Google Global Site Tag

This is a relatively new way to connect your site to your Google Analytics. Rather than installing the traditional GA script onto your site via the header, Global Site Tag is basically one script that communicates between your GA and all other services such as ads, remarketing, etc.

Google Tag Manager

Similar to the above, but works from the Google Tag Manager container and requires less JavaScript knowledge. It is a script that allows others to fire, so you just put this on your site and then control what it does through the GTM system. This can include tracking, events firing to GA, remarketing and more.

Which Should I Have Installed?


This is where it gets a little complicated. You essentially want the GA script to fire once per page and then use other scripts to do your further tracking.

This might mean just a GA script, just a GTM script, just Gtag or multiple. Either way, the output should be that your GA script is firing once, and your custom scripts are firing as needed.

So, if you’re using GTM or Gtag to fire your GA script, you don’t want a hardcoded GA script. We’ve seen this a few times, particularly when transitioning from one to another and the old code isn’t removed. A tell-tale sign of this is a sharp jump in your pages/session and a drop in bounce rates in GA.

Should I Switch?

Moving over to GTM or Gtag from the old GA script is a good idea. Personally, GTM is the preferred method, but it has quite a learning curve.

GTM is probably better for agencies or when numerous people use it as it relies on setting up custom triggers in a web interface.

Gtag is more useful from a development point of view and is better for those with JavaScript experience who don’t want to use an external system.

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Gary Hainsworth

Senior Organic Data Specialist

Having worked in SEO for over a decade, Gary knows everything worth knowing about search engines and technical SEO. A talented search marketer, Gary has worked for several exciting brands during his career to date, including the likes of the V&A, Warburtons, the NHS and the Lake District National Park. In his personal life Gary has a passion for guitars – be that playing them, modifying them or building them! He relates strongly with the humble and kind hedgehog, who also happen to be as prickly as his musical taste; anything loud, fast and angry.

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