GTM vs GA4: what each one does and when you need neither

GTM vs GA4 isn’t an either-or question, even though it’s almost always asked that way. Google Tag Manager puts tags on your website, and GA4 analyses what one of those tags sends. The real decision is a different one: how the tags get onto your site, and whether you need GA4 yet at all.

Below you’ll find the answer in one table, three setups that come up in practice, and the case where your website doesn’t need any of it yet.

1. GTM vs GA4: the answer in one table

Google describes Tag Manager as a tag management system for managing the tracking code on your website without changing the site’s code every time. A container bundles tags, triggers and variables: the tag is the script, the trigger says when it fires, and the variable feeds it values such as the order value. GA4, according to Google, shows you how people interact with your websites and apps across devices and platforms. For GA4 to see anything at all, a tag has to run on every page. Tag Manager can deliver that tag, but it can also sit directly in the code.

	Google Tag Manager (GTM)	Google Analytics 4 (GA4)
What it is	a distributor for tags	analysis of visits and events
What it does	loads tags from Google, Meta, Microsoft and others by rules you set	counts sessions, events and key events, shows reports
Shows you numbers	no	yes
Usable without the other	yes, for example just for Google Ads and the Meta pixel	yes, with the Google tag directly in the code
Cost	free (360 version for large companies)	free (360 version for large companies)
Consent in Germany	tags inside it only after consent; after a court ruling in Hanover, best to load the container itself only after consent too	yes, like any measurement that stores or reads information on the device

In short: GTM is the power strip, GA4 is one of the devices plugged into it. What a container needs for Google Ads in detail is in Google Tag Manager for Google Ads. For the overview of everything Tag Manager can and can’t do, see my Google Tag Manager guide.

2. Three setups with Google Ads, and which one fits you

If you run Google Ads, you almost always end up with one of three setups. They differ in who can make changes, how many platforms get data, and what costs money every month.

Setup A: GTM with GA4 and Google Ads

Tag Manager sits in the site’s code once. Inside it run the Google tag for GA4, the Google Ads conversion tag, the Conversion Linker and, if you need them, the Meta pixel or Microsoft’s UET tag. All of them wait for the answer in the cookie banner.

• Who it’s for: almost every website that advertises on more than one platform or counts forms, calls and bookings as conversions.
• Upside: changes without a developer, versions you can roll back to, third-party tags in the same system. In Google’s help, Tag Manager is the recommended option for anything beyond standard measurement.
• Catch: someone has to understand the container. A GTM where three agencies have left their tags behind quickly starts counting things twice.

How to set up GA4 in this setup and match its key events to your Google Ads conversions: Set up GA4 for Google Ads.

Setup B: just the Google tag (gtag.js), without Tag Manager

One Google tag can send data to several Google destinations, for example GA4 and Google Ads. Many website builders and shop systems add it without any code change once you enter the ID.

• Who it’s for: small sites that only use Google products and have one goal, such as a contact form with its own thank-you page.
• Upside: fewer moving parts. According to Google, the Google tag is enough if you only need standard measurement, meaning page views, clicks and scrolling.
• Catch: gtag.js only sends to Google products, and according to Google any further customisation means writing code. For Meta, LinkedIn or Microsoft you need a separate change to the site each time. And if the Google tag is hard-coded into the theme and your banner tool doesn’t control it, it loads before consent.

Setup C: server-side, with a second container on your own server

Here the browser sends its data to a server container on your own subdomain, and only the server passes it on to Google Ads, GA4 and Meta. You decide which data goes where, and in what form. You still need a web container or the Google tag in the browser, so setup C is added to A or B. It doesn’t replace them.

• Who it’s for: accounts with a meaningful budget and Smart Bidding, Meta advertising with the Conversions API, shops with long buying decisions.
• Cost: the server runs around the clock. For its own route via Cloud Run, Google quotes about 45 US dollars per server per month and recommends at least two instances. Hosted providers charge by usage.
• Catch: it’s no way around consent. No consent, no measurement, whichever server the tag fires on.

When it pays and which provider is enough to start with: Server-side tracking with GTM.

Which setup fits?

• You only run Google Ads and count one form: B is enough, though A is still the cleaner start.
• You run Google and Meta, or count several conversions: A.
• You spend enough each month that lost conversions noticeably skew your Smart Bidding: A plus C.

3. When your website doesn’t need any of it yet

There are sites where neither GTM nor GA4 does anything useful. It isn’t the norm, but it happens more often than tracking tutorials admit.

You don’t need either for now if all three of these are true:

• You don’t run advertising that learns from conversions.
• Nobody looks at the numbers regularly or makes decisions based on them.
• Your enquiries come in by phone or email, and you know where people come from anyway.

In that case GA4 mainly costs you obligations. In Germany, measurement needs consent under § 25 TDDDG, so you need a properly configured cookie banner, plus an entry in your privacy policy. What exactly applies is in Tracking and consent in Germany.

What you can use instead:

• Google Search Console: shows which search queries your site appears for in Google Search, how often, and how often people click. A domain property is verified with a DNS record, with no script on the site.
• Calls from ads: if you do have a small Google Ads account for phone calls, Google records calls from the ad as conversions through call reporting with a Google forwarding number. The caller never visited your website. According to Google, this is available in Germany and Switzerland, among others. Austria isn’t on the list.

Once you run Google Ads with form or booking conversions, that changes. The account then only learns from what you measure, and without a conversion tag Smart Bidding is flying blind. From that point you need at least setup B, and A is better.

The bottom line

• GTM delivers tags, GA4 analyses data. The question isn’t GTM or GA4, it’s how the tags get onto your site.
• Google Ads conversions can be measured without GA4, with the Google tag directly in the code or through Tag Manager.
• Setup A, GTM with GA4 and Google Ads, is the right start for most advertising websites.
• Setup B, just the Google tag, is enough for small sites with one goal and only Google products.
• Setup C, server-side, comes on top once the budget is big enough that lost conversions cost money. It replaces neither the browser part nor consent.
• Without advertising that learns from conversions, and without anyone reading the numbers, Search Console is enough.

Not sure which setup fits your website? That choice is exactly a question for the Clarity Session: from €390, a 60-minute video call. Afterwards you know which setup you need, what you can leave out and in which order to go about it. If you’d rather have your existing measurement checked, the conversion tracking audit covers that. Whether the session fits is something you can check first in a free intro call. Book a free intro call.

FAQ

Can I use GA4 without Google Tag Manager?

Yes. You can put the Google tag directly into the code of every page, or add it through your website builder’s or shop system’s integration. You don’t need Tag Manager for that.

Do I need GA4 to measure Google Ads conversions?

No. Google Ads measures conversions with its own tag, in the code or through Tag Manager. You only need GA4 if you want to import key events from GA4 or see how visitors behave per keyword.

Can I run gtag.js and Tag Manager at the same time?

Google says that if you use Tag Manager, you don’t need to add extra gtag.js code to your site. If both run in parallel and send to the same property, you can easily count twice. Pick one route.

Is Google Tag Manager free?

Yes. Google offers GTM and GA4 for free; the 360 versions are meant for large companies. With server-side tagging, though, you pay for the server.