UA to GA4: everything you need to know for a smooth transition

If you're reading this, chances are you've either just migrated from Universal Analytics to GA4, or you're helping clients who are still figuring out this new world. Either way, welcome to the club.

Universal Analytics officially stopped processing data on July 1, 2023, and as of July 2024, you can no longer access those old UA properties at all. The historical data? Gone. So if you're still holding onto hopes of retrieving that old data, I'm sorry to be the bearer of bad news.

But here's the thing: GA4 isn't just "new Google Analytics." It's a completely different beast. Let me break down what actually changed and why it matters for your day-to-day analytics work.

The fundamental shift: sessions vs events

This is the biggest change, and honestly, it took me a while to wrap my head around it.

In UA, everything revolved around sessions. A user came to your site, did some stuff, left. That was a session. Pretty straightforward.

In GA4, everything is an event. Page views? Event. Button clicks? Event. Scrolls? Event. This might sound like semantics, but it fundamentally changes how you think about and analyze your data.

Pro tip: Stop thinking about "what happened in this session" and start thinking about "what actions did this user take." It's a subtle but important mental shift.

What you lose (and what you gain)

Let's be real about the trade-offs.

What's gone

• Views - Remember setting up filtered views for internal traffic? That concept doesn't exist in GA4. You now use data filters at the property level.
• Bounce rate (kind of) - It's been replaced by engagement rate, which is actually more useful. A bounced session in UA was any single-page session. In GA4, you have "engaged sessions" (10+ seconds, or a key event, or 2+ page views).
• 50 months of data retention - GA4 free gives you 14 months max for exploration reports. Standard reports keep aggregated data forever, but if you want granular access, connect BigQuery early.

What's new and actually good

• Cross-platform tracking - Finally, you can track web and app users in the same property.
• Free BigQuery export - This was a GA360-only feature. Now everyone gets it.
• Better privacy defaults - IP anonymization is on by default.
• Predictive metrics - GA4 can predict purchase probability and churn likelihood (with enough data).

Key terminology changes

Here's where it gets confusing for anyone used to UA:

UA Term              →  GA4 Term
-----------------------------------------
Goals                →  Key Events (was "Conversions" until March 2024)
Bounce Rate          →  Engagement Rate (inverse logic)
Views                →  Data Streams
Hit                  →  Event
Category/Action/Label →  Event parameters

Speaking of that terminology change: in March 2024, Google renamed "Conversions" to "Key Events" in GA4. If you're connecting to Google Ads, those become "Conversions" in Ads, but within GA4 itself, they're called Key Events. Confusing? Yes. Important to know? Absolutely.

The hierarchy: understanding the new structure

GA4 uses a different organizational hierarchy:

Account
  └── Property
        └── Data Stream (Web)
        └── Data Stream (iOS App)
        └── Data Stream (Android App)

One GA4 property can have multiple data streams, which is how you get that cross-platform view. But here's an important gotcha: don't create multiple web data streams for the same site. That leads to data duplication and reporting chaos.

For more details on how to set this up correctly, check out our GA4 properties and data streams guide.

What you actually need to do

If you're setting up GA4 for the first time (or auditing an existing setup), here's the checklist:

1. Create your GA4 property - One property per brand/product
2. Set up your data stream - Usually just one web stream
3. Install the tracking code - Via Google Tag Manager (preferred) or direct code
4. Configure data retention - Change from 2 months to 14 months immediately
5. Set up your key events - Map your old goals to new key events
6. Link your Google accounts - Ads, Search Console, BigQuery
7. Exclude internal traffic - Create filters for your team's IPs

Don't skip this: The default 2-month data retention means you lose access to detailed data in Explorations after 2 months. Go to Admin → Data Settings → Data Retention and change it to 14 months.

The metrics that actually matter now

In GA4, focus on these core metrics:

Notice how everything is about engagement, not just presence. A user who bounced immediately doesn't count the same as someone who spent 5 minutes reading your content. That's a good thing.

Making sense of the reports

GA4's reporting interface is... different. The old familiar reports are gone, replaced by:

• Reports Snapshot - Your at-a-glance overview
• Realtime - Live activity (now with users in last 5 minutes)
• Life Cycle Reports - Acquisition, Engagement, Monetization, Retention
• User Reports - Demographics and tech details

For custom analysis, you'll spend most of your time in Explorations (formerly Analysis Hub). It's powerful but has a learning curve.

If you're finding the GA4 interface overwhelming, tools like Analayer can help you get cleaner visualizations without the learning curve. Worth checking out if you manage multiple properties.

Common migration mistakes

I've seen these repeatedly when helping agencies transition:

1. Not mapping old goals properly - Your UA goals need to be recreated as GA4 key events
2. Forgetting about filters - Internal traffic doesn't filter itself
3. Ignoring the consent requirements - GA4 works with Consent Mode v2, which is now required in many regions
4. Comparing UA and GA4 data directly - The data models are too different. Set a baseline in GA4 and measure from there.

The bottom line

GA4 is a significant change, but it's not inherently worse. It's just different. The event-based model is actually more flexible once you get used to it. The privacy features are better. The cross-platform tracking is genuinely useful.

The learning curve is real, but you're not alone. Start with the basics, set up your tracking correctly, and build from there.

If you want a simpler way to visualize your GA4 data without wrestling with the interface, try Analayer for free. We built it specifically for people who need clean, actionable analytics without the complexity.