Ad blockers and your GA4 numbers: what you lose and what you can recover

Every ad blocker stops Google Analytics by default. Visitors who use one don't show up in GA4, their purchases don't reach Google Ads or Meta, and nothing in your reports tells you how many there were. How big that gap is depends on your audience: technical and younger audiences on desktop block far more than shoppers on a phone.

What ad blockers look for

Blockers work from filter lists. Those lists match two things:

• Domains: googletagmanager.com, google-analytics.com, connect.facebook.net and hundreds of other tracking domains.
• Patterns in the address: /gtm.js?id=GTM-, /g/collect, /gtag/js and similar fixed paths, on any domain.

What server-side tagging on your own subdomain recovers

Loading Tag Manager and sending hits through your own tagging subdomain gets past the domain lists: your subdomain isn't on them. It does not get past the pattern rules. A request to mbase.yourshop.com/g/collect still matches /g/collect, and plenty of blockers stop it.

What masking adds

That is the gap Measurebase's Enhanced script and Enhanced Ad Blocker Protection close. The script loads from a path unique to your domain, with nothing in it that says "gtm", and every tracking request after that goes to a random path with an encoded payload that looks different every time. There is no fixed pattern left to match. Your tagging server decodes the requests before they reach your server container, so nothing changes in GTM.

With Same-Origin Tracking on top, the requests go to a path on your own website, so there isn't even a separate tracking subdomain to put on a list.

How much it recovers for you

The Enhanced Ad Blocker Protection page shows which share of the masked requests came from browsers with an ad blocker: the traffic that would most likely have been lost. Read it as a minimum. Blockers that only work on network level, like a DNS blocker or Brave's default mode, can't be detected from the page.

What no setup recovers

• Visitors who block JavaScript entirely.
• Blockers that hide or block everything that looks like tracking based on behaviour rather than lists. These are rare, but they exist.
• Visitors who refused consent. That isn't blocking but a choice, and it should be respected; see Tags that fire before consent.

Frequently asked questions

Is it allowed to get past ad blockers?

Masking changes how requests look, not what you are allowed to collect. Consent rules apply exactly as before: a visitor who refused tracking must not be tracked, whatever their browser does.

Does Google's own tag gateway do the same?

Google tag gateway serves Google's tags from your own domain, which gets past the domain lists for Google tags only. It doesn't mask the request patterns and doesn't cover Meta, TikTok or other platforms.