Guide · Measurement
Google Analytics 4: What Is GA4 and What Changed
Google Analytics 4, or GA4, is the current version of Google's web and app analytics tool, and it fully replaced Universal Analytics in 2024. This guide explains how GA4 measures visits, what changed from the old version, the settings that trip people up and what to check in any agency's GA4 report.
What GA4 is
GA4 is a type of Google Analytics property. It collects data from both websites and apps, so you can see a customer journey across the two in one place.
Google lists its main features as:
- It uses event-based data instead of session-based data.
- It includes privacy controls such as cookieless measurement and behavioural and key event modelling.
- It offers predictive features without complex models.
- It links directly to media platforms such as Google Ads, so you can act on what you learn.
Sources: Google Analytics Help, Introducing the next generation of Google Analytics
The end of Universal Analytics
Universal Analytics (UA) was the version most businesses used before GA4. Google shut it down in two stages.
Date What happened 1 July 2023 Standard UA properties stopped processing new data 1 July 2023 to 1 July 2024 UA 360 properties with a current 360 order got a one-time processing extension 30 June 2024 Last day to request BigQuery export and backfill of UA 360 history Week of 1 July 2024 Access to all UA data, the interface and the API ended for most users Google's advice was to export old UA data before July 2024. If that was not done, those old reports are gone. A GA4 property does not bring them back. Tools that read UA through the API, such as Looker Studio, also stopped showing UA data.
This matters when you compare years. A report that shows "growth since 2022" may be setting old UA numbers against new GA4 numbers. The two count things differently, so the comparison may not hold.
Sources: Google Analytics Help, Universal Analytics is going away
Events instead of sessions
The biggest change is how GA4 records activity. UA built its reports around sessions, meaning a visit with page views inside it. GA4 records almost everything as an event: a page view, a scroll, a click, a form sent or a purchase.
Each event can carry extra details, called parameters, such as the page title or the value of a sale. Reports are then built by counting and grouping those events.
For a business owner, this means two things. First, many numbers in GA4 will not match the old UA numbers, even for the same site. Second, what GA4 can tell you depends on which events are set up. If no one set up an event for a form being sent, GA4 cannot report on form leads.
Sources: Google Analytics Help, Introducing the next generation of Google Analytics
Key events and conversions
In GA4, the actions that matter most to your business are now called key events. Google made the change to bring Analytics and Google Ads into line, because the two used to count conversions differently.
The word "conversion" now refers to an action you use to measure Google Ads performance. So a "lead form sent" event might be a key event in GA4 and also a conversion in Google Ads.
If an agency report still talks about "GA4 conversions" and the numbers do not match Google Ads, this naming change is a good first thing to check.
Sources: Google Analytics Help, Conversions vs. key events in Google Analytics
Data retention: the setting most people miss
GA4 keeps detailed user-level data only for a set time. In a standard GA4 property you can choose:
Data type Standard GA4 choices GA4 360 extra choices User-level data, including key events 2 months or 14 months Not listed for this data type Other event data 2 months or 14 months 26, 38 or 50 months Age, gender and interest data Always 2 months Always 2 months Google says the retention setting affects explorations and funnel reports, the tools for custom analysis. Standard reports are not cut. Data past the retention period is deleted automatically each month. So if the setting was left at 2 months, a detailed look back at last year is not possible, and the deleted data cannot be brought back.
Getting started with GA4
- Create a Google Analytics account and a GA4 property for your business.
- Add a web data stream for your site, and app streams if you have apps.
- Put the Google tag on every page, or set it up through Google Tag Manager.
- Turn on the events you need, and mark the important ones as key events.
- Set data retention to the longest option your plan allows.
- Link Google Ads if you run ads, so key events and ad conversions line up.
- Give team members and agencies their own access, rather than sharing one login.
Google's help centre has a step-by-step guide, including setup through a website builder or Google Tag Manager. If you use an agency, make sure your business, not the agency, owns the GA4 account.
Sources: Google Analytics Help, Set up Analytics for a website and/or app; Google Analytics Help, Data retention; Google Analytics Help, Conversions vs. key events in Google Analytics
Seven questions to ask about an agency's GA4 report
Most GA4 guides teach setup. Buyers need the other side: how to tell if a report can be trusted. Ask these before you accept any GA4 numbers.
Question Why it matters Who owns the GA4 property? If the agency owns it, you can lose your history when you leave Which events are key events, and why? A report can look good by counting easy actions, such as scrolls, as key events Does the key event count match Google Ads conversions? A gap is normal, but the agency should explain it What is the data retention setting? At 2 months, deep year-on-year analysis is not possible Does any chart compare GA4 with old UA numbers? The two count differently, so the trend may be false Is your own team's traffic filtered out? Staff visits can inflate small sites Can you see the raw report, not just a slide? A screenshot cannot be checked Pair these questions with the evidence checks in briefing an agency. The editors' conversion optimization category notes show how they read measured results. For how the paid side is counted, see our SEO vs SEM guide.
Sources: Google Analytics Help, Conversions vs. key events in Google Analytics; Google Analytics Help, Data retention; Google Analytics Help, Universal Analytics is going away
Frequently asked questions
What is Google Analytics 4?
Google Analytics 4, or GA4, is the current version of Google Analytics. It collects website and app data together and records activity as events instead of sessions.
Is Universal Analytics still available?
No. Standard Universal Analytics stopped processing data on 1 July 2023, and access to all Universal Analytics data, the interface and the API ended from the week of 1 July 2024.
What is the difference between GA4 and Universal Analytics?
GA4 uses an event-based model and combines web and app data, while Universal Analytics was built around sessions and page views. Numbers from the two often do not match.
What are key events in GA4?
Key events are the actions most important to your business, such as a lead form being sent. Google renamed them from conversions so that "conversion" now refers to actions used in Google Ads.
How long does GA4 keep data?
In a standard property, user-level and event data can be kept for 2 months or 14 months. GA4 360 adds 26, 38 or 50 months for event data. Age, gender and interest data is always kept for 2 months.
How do I install Google Analytics 4?
Create a GA4 property, add a web data stream, and put the Google tag on every page directly or through Google Tag Manager. Then set up key events and data retention.
Sources
- Google Analytics Help, Introducing the next generation of Google Analytics
- Google Analytics Help, Universal Analytics is going away
- Google Analytics Help, Conversions vs. key events in Google Analytics
- Google Analytics Help, Data retention
- Google Analytics Help, Set up Analytics for a website and/or app