Does Google Analytics 4 Use Cookies?

Chances are you’ve seen the term "cookieless future" pop up more and more in marketing blogs and tech news. With Google phasing out third-party cookies in Chrome and privacy regulations tightening, it’s fair to wonder how your analytics will be affected. This post will demystify how Google Analytics 4 uses cookies and explain how its design prepares you for a world with less cookie-based tracking.

The Short Answer: Yes, GA4 Uses Cookies (But It’s Not the Whole Story)

Let's get straight to the point: Yes, Google Analytics 4 uses first-party cookies by default. However, it was built from the ground up to be far less dependent on them than its predecessor, Universal Analytics (UA). While UA relied almost entirely on cookies to track users and sessions, GA4 has a more flexible, event-based data model that can operate with or without them.

This dual approach is GA4’s biggest strength. It allows you to continue gathering essential session and user data through traditional cookies when users consent. But when they don’t consent, or when cookies are blocked, GA4 can use cookieless methods and machine learning to fill in the data gaps. Think of it as having both a primary engine and a powerful backup generator, ensuring your analytics keeps running smoothly no matter the conditions.

What Cookies Does GA4 Use?

Unlike Universal Analytics, which used several different cookies, GA4 simplifies things significantly by relying on just two primary first-party cookies:

• _ga: This is the main cookie used to distinguish between users. It works by assigning a randomly generated "Client ID" to each visitor. Whenever a user returns to your site, GA4 reads this ID to recognize them as a returning user rather than a new one. By default, this cookie expires after two years, but you can adjust its lifespan.
• ga<container-id>: This cookie is used to maintain session state. Its main job is to store and update information about a user's current session, like which page they're on and how long they've been browsing. It’s a session-based cookie, meaning it expires as soon as the browsing session ends or after a short period of inactivity.

These two cookies do the heavy lifting for GA4's standard tracking. The Client ID helps measure user counts and retention, while the session cookie helps track user engagement and behavior across an individual visit. Together, they allow you to answer fundamental analytics questions like, "How many new versus returning users came to our blog last month?"

Why First-Party Cookies Are Different (and More Acceptable)

The distinction between first-party and third-party cookies is central to the entire privacy movement sweeping the web. GA4's complete reliance on first-party cookies is a deliberate, privacy-conscious choice.

What Are First-Party Cookies?

First-party cookies are set by the website domain you are currently visiting. When you go to yourwebsite.com, a cookie created by yourwebsite.com is a first-party cookie. These are generally considered safe and useful. They help a site remember your login information, save items in your shopping cart, and recognize you when you come back. In the case of GA4, they help the site owner understand user traffic and engagement without sharing that information across the web.

What Are Third-Party Cookies?

Third-party cookies are set by a domain other than the one you're visiting. They are typically placed by ad-tech platforms or social media widgets embedded on a site. For example, if yourwebsite.com has a "like" button from a social media platform, that platform might place a cookie in your browser. This cookie allows them to track your browsing activity not just on your website but across any other site that uses their widget.

This cross-site tracking capability is what has made third-party cookies so controversial and is why browsers like Safari, Firefox, and now Chrome are phasing them out. Because GA4 exclusively uses first-party cookies, it's more durable and respectful of user privacy, as it doesn't track individuals across different websites.

How GA4 Prepares for a "Cookieless" World

GA4's true innovation isn't just its use of first-party cookies, it's how it functions when cookies aren't available at all. This is where consent mode and behavioral modeling come into play.

Step 1: Google Consent Mode

To comply with regulations like GDPR and CCPA, you must ask for user permission before placing any analytics or marketing cookies on their device. This is usually done through a cookie consent banner.

Google Consent Mode is an intelligent feature that allows your GA4 tags to adjust their behavior based on the user's consent choice. Here’s how it works:

• If a user grants consent: The GA4 tags fire normally, setting the _ga and _ga_... cookies to collect detailed user and session data. Business as usual.
• If a user denies consent: The GA4 tags will not set any cookies. Instead, they send "cookieless pings" to Google Analytics. These are anonymized, aggregated signals that communicate that certain events occurred (like a page view or a conversion) but without any user-level identifiers.

By collecting these cookieless pings, you can still measure basic site traffic and conversion events without violating user privacy.

Step 2: Behavioral Modeling for Conversions

Losing observed data from users who deny consent can create significant gaps in your reporting, making it hard to understand campaign performance or customer journeys. GA4 solves this with behavioral modeling.

When you have enough cookieless pings and observed data from consenting users, GA4 activates machine learning models. It analyzes the behavior and conversion patterns of your consenting users to estimate the behavior of your non-consenting users. This modeled data is then blended with your observed data to provide a more complete, privacy-safe picture in your reports.

For example, if you see 100 conversions from your consenting users, behavioral modeling might estimate that an additional 20 conversions likely came from your non-consenting user group, giving you a more accurate total.

Step 3: Google Signals and Other Identifiers

GA4 also uses other identifiers to enrich data without cookies. If you enable Google Signals, GA4 can associate session data with users who are signed into their Google accounts and have enabled Ads Personalization. This allows GA4 to create more accurate cross-device user journey maps. For example, it can recognize that a user who saw an ad on their phone and later converted on their desktop is the same person - all without depending on third-party cookies.

What This All Means for You: An Actionable Checklist

Now that you understand the mechanics, here's how to prepare your website and analytics for this modern data landscape:

1. Update Your Privacy Policy: Ensure your privacy policy clearly states that your site uses first-party cookies from Google for analytics purposes. Transparency is essential for building trust.
2. Implement a Proper Cookie Consent Banner: If you don’t have one already, install a cookie consent banner. This is not optional. It's a legal requirement in many regions. Make sure it gives users a clear choice to accept or reject non-essential cookies.
3. Configure Google Consent Mode: Once your banner is in place, configure Google Consent Mode. This tells GA4 how to respond to user choices, enabling cookieless pings and behavioral modeling when necessary. Many consent management platforms (CMPs) have built-in integrations to make this simple.
4. Enable Google Signals: Log in to your GA4 account and enable Google Signals. This gives you access to more robust user data, better demographics reports, and critical cross-device insights that are invaluable in a cookieless world.
5. Trust the Modeled Data: Start getting comfortable with the fact that not all data will be 100% "observed." Modeled data is a statistically sound way to fill gaps created by privacy choices, and it's far better than having no data at all. Understanding and trusting these blended datasets is key to making informed decisions.

Final Thoughts

While GA4 does use first-party cookies to identify users and track sessions, its real power lies in its ability to function without them. By combining cookieless pings, behavioral modeling, and Google Signals, GA4 offers a privacy-forward solution that is resilient, flexible, and built to thrive in a world where user consent and data privacy are paramount.

Understanding and interpreting this mix of observed and modeled data from GA4 can still feel overwhelming, especially when you need quick answers. We built Graphed to cut through that complexity. Instead of wrestling with GA4 reports, you can connect your analytics in seconds and just ask questions in plain English - like "Which marketing channels brought in the most new users last month?" - and get back clear dashboards and insights in real time, automatically.