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I’m using the UA tag to populate both my original UA account as well as GA4, and the users and page view difference is absolutely astounding. Probably like a 20% discrepancy in UA’s favor. UA is set to exclude bots.

Is anyone else having a similar experience?

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  • Latest Post Latest Post by odeskavita
AussieWebmaster commented: also seeing more in UA - but maybe 10% - have to set up GA4 filters next +4

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Short summary: the 10-20% user gap you reported is common when running Universal Analytics and Google Analytics 4 side-by-side. already found the official note that the platforms count users differently; here are the practical reasons you won't get identical totals and a short checklist to diagnose the gap.

Why they differ (practical causes)

  • GA4 uses an event-based model and reports "active" users tied to the automatic user_engagement event. A quick page load that never generates engagement can be counted in UA but not in GA4.
  • Sessionization and attribution rules differ (session_start in GA4, campaign/session boundary rules differ from UA), so the same visit can be split or merged differently.
  • Tagging/implementation differences: dual-tag setups can accidentally double-fire, drop, or block hits depending on how the tag is configured or whether Consent Mode/ad‑blockers interfere.
  • Filters and traffic rules are different. As reminded, some UA settings (filters, custom dims) do not migrate automatically — GA4 needs its own definitions and data-filter configuration.

Quick diagnostic checklist

  1. Reproduce in a clean browser (incognito, no extensions) and watch UA Real‑Time vs GA4 DebugView to see who registers and what event fires.
  2. Verify the tag fires exactly once per page for each property (use Tag Assistant or the network panel).
  3. Confirm time zone and date-range match between properties.
  4. Check GA4 internal-traffic rules, data filters, and whether Google signals or user_id are enabled (these change user stitching).
  5. Test with and without common ad‑blockers or Consent Mode active.
  6. If needed, reconcile with server logs or a known test user to see which product is closer to reality.

Actionable takeaway: run both in parallel, use these tests to narrow the cause, and treat GA4 as a distinct measurement system — optimize for consistent event definitions rather than exact numeric parity.

Member Avatar for Dani

Thanks Frank :) I migrated my filters and audiences over last week myself.

But you have to admit it’s a rather confusing experience if Google leaves so much discrepancy between two products that are literally running off the exact same javascript tag.

Do you happen to know if they’ve announced anything publicly that can account for the discrepancy? Eg as simple as an announcement that GA4 has better bot filtering detection. That sorta thing?

Member Avatar for Dani

So I uncovered this article at which explains that G measures users differently between the two platforms. For what it’s worth, I do only have a 2% discrepancy for page views.

Member Avatar for web2tech

Your existing UA custom dimensions and metrics tags may migrate over fine to GA4, but you will still need to set up the dimensions and metrics in the GA4 property interface. To set up custom dimensions and metrics in the interface, refer to Google's setup guide.

Member Avatar for odeskavita

I think migrating from UA Analytics to GA4 is probably the best thing to do. It lets you track people across platforms and devices. This enables you to understand better how customers engage with your business, whether using your website, your mobile app, or both.

The best part I liked about this analytics is that it makes tracking conversions considerably simpler because you can view the whole user experience from beginning to end, regardless of the platform or device the user is using.

Those who haven't migrated to GA4 should do it now, as, by July 2023, Google will discontinue Universal Analytics.

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