Google Analytics 4: how does GA4 work?

What is Google Analytics 4 (GA4)?

Google Analytics 4 is the current version of Google Analytics, available at analytics.google.com, where you create the account and the property.

Google introduced it on October 14, 2020, building on the App + Web property launched in beta in 2019. Its help center now simply says “Google Analytics”. The tool is “free of charge”; a paid version, Analytics 360, raises several of the limits mentioned here.

GA4 is only a tool: goals, KPIs and the tracking plan are set beforehand, following our web analytics method.

What changed compared with Universal Analytics

Universal Analytics (UA), the previous generation, differs from GA4 on five points.

Google announced the end of Universal Analytics on March 16, 2022. Since July 2024, the old data can no longer be accessed, and Google has permanently deleted the data that had not been exported.

So there is no GA4 migration left to do in the sense of a switchover. Since March 2023, Google has automatically created a GA4 property for UA properties that had not migrated, unless they opted out. If your site received one, review it as you would a new property.

How does GA4 measure a website?

GA4 records each interaction as an event, along with parameters that describe it. A page view is the page_view event; its title (page_title) and the previous page (page_referrer) are its parameters.

Some events are collected automatically, others through enhanced measurement, which you can turn on without touching the code. Your own events are unlimited in number for a web stream.

Listening to history changes matters for JavaScript websites: navigation without a page reload still produces a page view. Google also asks you to check that no enhanced measurement event collects personal data.

Any event can become a key event: a star in Admin > Events is enough. A standard property accepts 30 of them, a 360 property accepts 50, and purchase is marked by default. The word “conversion” now refers to the action used to measure ad campaigns and to drive Google Ads automated bidding.

Collection has its limits. An event carries at most 25 parameters. A standard property accepts 50 event-scoped custom dimensions, 25 user-scoped ones and 50 custom metrics (125, 100 and 125 in 360).

How do you install Google Analytics 4 on a website?

Installation takes two steps: create the property, then place the Google tag on the site, directly, through Google Tag Manager or through your CMS.

1. Create a Google Analytics account and choose its data sharing settings.
2. Create a property (an account accepts up to 2,000).
3. Add a web data stream for your site.
4. Note the Google tag ID, which usually starts with “G-” (Admin > Data streams).
5. Install the tag with one of the three methods in the table.
6. Turn on debug mode and check in DebugView, in real time, that events are coming in.

Site Kit by Google has more than 5 million active installations according to WordPress.org (checked on October 19, 2026).

Google Tag Manager: what changes in October 2026

The Tag Manager release notes report three changes that affect GA4.

• July 9, 2026: a container loaded with a product ID (G-XXXX, AW-XXXX) only accepts Google tags and variables; with a GTM-XXXX ID, it is not restricted.
• October 8, 2026: all containers initialize on load, whatever the gtag('config') commands, which now appear in the dataLayer as gtag.config events.
• October 12, 2026: a container can send data directly to Google’s measurement products, without also loading gtag.js.

Which settings should you configure when you create the property?

These settings are made in the property’s admin, as soon as it is created.

• Data retention: choose 14 months, the maximum in standard. According to the help page on data retention, this setting only affects explorations and funnels, not standard reports. The default value is not stated there: check it.
• Internal traffic: declare your team’s IP addresses (traffic_type parameter), then turn on the filter. A property accepts 10 data filters; an applied filter is permanent, and the excluded data is never processed, neither in Analytics nor in BigQuery.
• Hostname: since September 21, 2026, an include filter only accepts the domains on your list; it blocks events with no hostname and does not apply to the Measurement Protocol. Exclusion by hostname has existed since June 11, 2026.
• Data sharing: with the “Google products & services” setting, Google can use your data to improve its products, and it is an independent controller of that processing under the GDPR.
• EU data: settings by region turn off Google signals and granular device and location data.
• Consent mode: to be set up with your cookie banner (GDPR section below).

Then link the property to Google Search Console and, if you advertise, to Google Ads, whose linked data is kept for a rolling 36 months. For raw data, BigQuery export is available (limits below).

Which reports and metrics should you read in GA4?

GA4 is read at three levels: standard reports, explorations (detailed analyses, funnels) and dashboards. Released on September 9, 2026, dashboards bring your KPIs together in a single report.

Since February 10, 2026, the Home page shows generated insights that summarize the top three data changes since your last visit. Since August 11, 2026, the click-through conversion window can be set from 1 to 90 days.

Data thresholds, set by the system and not adjustable, hide some rows, especially demographic data and search queries.

Funnel explorations show the step where visitors drop off: this is the starting point for conversion rate optimization.

The “AI Assistant” channel: measuring traffic from ChatGPT

Since May 13, 2026, the default channel group includes an “AI Assistant” channel. According to Google Analytics Help, it groups visits from ChatGPT, Gemini, Deepseek, Copilot or Grok; the launch note also mentions Claude.

The rule relies on the referrer URL. If the referring site is on Google’s list of AI assistants, the visit gets the medium “ai-assistant” and the campaign “(ai-assistant)”. The channel excludes Google’s AI Overviews and AI Mode.

On June 11, 2026, Google added the “Source group” dimension, which brings scattered sources together (Facebook, Instagram, TikTok…). It includes a grouping for ChatGPT (OpenAI) and Perplexity, also applied to past data.

Is GA4 GDPR compliant in France?

It all depends on the configuration: consent or the exemption conditions of the CNIL (the French data protection authority), consent mode, data sharing. For transfers to the United States, Google states that it complies with the Data Privacy Framework, recognized by the European Commission on July 10, 2023. What follows summarizes the facts published by Google and the CNIL, not legal advice.

Modeling requires two thresholds. The first: at least 1,000 events per day with analytics_storage='denied' for at least 7 days. The second: at least 1,000 users per day with analytics_storage='granted' for at least 7 of the previous 28 days.

GA4 does not store IP addresses. Traffic from the EU, the United Kingdom and Switzerland is collected by servers located in those areas, and the IP is only used there for approximate geolocation before being deleted.

Since the European Commission’s adequacy decision of July 10, 2023, the CNIL states that transfers to certified US entities can take place freely. It adds that changing only how the IP address is processed is not enough, and that proxying remains good practice.

According to the CNIL, audience measurement trackers are exempt from consent in France if they are used only for measurement, solely on behalf of the publisher. They must also produce anonymous statistics, with no cross-referencing or transfer to third parties.

An offering whose provider reuses the data for its own purposes falls outside this exemption; some let you turn off that reuse. The page does not name any tool: so look closely at the “Google products & services” setting. The CNIL also recommends a 13-month lifetime for trackers and 25 months of data retention.

What are the limits of GA4?

Google Analytics 4 underestimates traffic as soon as visitors refuse cookies, and its reports hide or cap some data.

• Consent: modeling of refusals remains out of reach for a site with fewer than 1,000 consenting users per day.
• Thresholds: some rows stay hidden, with no setting to change it.
• History: 14 months at most in explorations in standard.
• Volumes: one million events exported per day to BigQuery in standard, 20 billion in 360.

If these limits block your use case, our selection of analytics tools presents other solutions. Elev8 Lab has no commercial relationship with the vendors mentioned.