How to track AI traffic in GA4: ChatGPT, Perplexity, Gemini and more

Yes, for visits that arrive with a referrer or a UTM tag. On May 13, 2026 Google added an AI Assistant channel to the GA4 default channel group, for users who reach your site from chatbots such as ChatGPT, Gemini and Claude^[2]. GA4 sets the medium to ai-assistant when the referrer matches its list of AI assistants^[1]. If you open Reports > Acquisition > Traffic acquisition with the session default channel group, AI Assistant now shows as its own row.

That built-in channel is a good start, but it has two gaps. Google describes the assistants it covers by example and does not publish the full list, and it explicitly excludes Google's AI Overviews and AI Mode^[1]. The steps below add a regex-based view you control, then cover what Search Console and Bing report for AI features.

Use one regex for session source in every report, exploration and channel rule, so your numbers agree. This one matches the hostnames of the common AI assistants, with or without a subdomain:

^(.*\.)?(chatgpt\.com|chat\.openai\.com|perplexity\.ai|gemini\.google\.com|bard\.google\.com|copilot\.microsoft\.com|claude\.ai|deepseek\.com|grok\.com|chat\.mistral\.ai|meta\.ai)$

• ChatGPT: OpenAI says ChatGPT automatically adds utm_source=chatgpt.com to links in ChatGPT search results, so those visits show chatgpt.com as the source even when no referrer is passed^[4].
• Filter on source, not medium. Depending on whether a visit carried a UTM tag or only a referrer, the medium can differ, while the source stays the same.
• Maintain it. Check your referral report monthly for new AI hostnames and add them. Google gives the same advice for its own example^[3].

An exploration is the quickest way to see AI traffic by engine and landing page, and it changes nothing in your property. It takes about five minutes:

1. In GA4, go to Explore and start a Blank (free-form) exploration. Name it "AI referral traffic".
2. Set the date range to the last 90 days, or longer if your traffic is small.
3. Import dimensions: Session source, Session source / medium, Landing page + query string and Session default channel group.
4. Import metrics: Sessions, Engaged sessions, Key events and, for stores, Total revenue.
5. Drag Session source into Rows and the metrics into Values.
6. Add a filter: Session source matches regex, and paste the regex above.
7. Add Landing page + query string as a second row dimension to see which pages AI assistants send people to.
8. Compare with Session default channel group to spot AI sources that GA4's built-in channel classifies elsewhere.

The landing pages are often the most useful output. A software company in Canada might find that ChatGPT sends people to a comparison page, while Perplexity sends them to documentation. A retailer in Spain might see AI visits concentrated on a returns policy page. Those pages are what the engines trust, so keep them accurate.

A custom channel group makes your AI definition available in standard reports, not only in explorations, and it can be applied to past data retroactively^[3]. You need the Editor role or above on the property, and standard properties can have two custom channel groups (five on GA4 360)^[3].

1. Go to Admin > Data display > Channel groups^[3].
2. Copy the default channel group so you keep all the standard channels, and name it, for example, "Channels with AI (custom)".
3. Add a new channel called "AI assistants (custom)" with the condition Source matches regex, and paste the regex.
4. Reorder the channels so the new one sits above Referral. GA4 puts traffic in the first channel whose definition it matches^[3].
5. Save the group, then select it in the Traffic acquisition report from the channel group dimension picker.

Keep the built-in AI Assistant channel in view alongside your custom one. If they disagree by a lot, look at which sources differ: either GA4 recognizes an assistant you've missed, or your regex catches one Google doesn't list.

Clicks from AI Overviews and AI Mode can't be separated in GA4. They come from Google Search, so they arrive as Google organic traffic, and Google says its AI Assistant channel excludes them^[1]. Search Console is the only place Google reports on them, and it does so in two ways.

• The Performance report includes appearances in AI features in your overall search traffic, under the Web search type, mixed in with regular results^[5].
• The Generative AI performance report shows impressions, meaning how often links to your site were shown in AI Overviews and AI Mode. Google says it reached all websites worldwide by August 31, 2026^[6].

The Generative AI report has firm limits. It counts impressions only, without clicks or queries; it combines AI Overviews and AI Mode; and it breaks data down by page, country, device and date^[6]. Two links from the same site in one AI answer count as a single impression, the usual Search Console row limits apply, and the report doesn't appear if your site has too few AI impressions^[6]. Find it in Search Console under the Performance reports^[6]. For more on how these features choose sources, see Google AI Overviews and AI Mode.

Microsoft offers a similar view for its own products. Bing Webmaster Tools' AI Performance report, introduced in February 2026, shows how often your pages are cited in Microsoft Copilot, AI summaries in Bing and some partner integrations, plus the grounding queries that retrieved them. It measures citations, not clicks^[7]. Copilot tracking in Glossy Data is coming soon; see Copilot.

AI referral numbers in GA4 are a floor, not the total effect of AI on your business. Expect them to undercount for several reasons:

• Missing referrers. Browsers send only the origin across sites by default, and a no-referrer policy strips it entirely^[8]. Native apps and some in-app browsers may not pass one either. Visits with no referrer and no UTM tag land in Direct^[1].
• Copied links. Someone who copies a URL from an answer into a new tab arrives as Direct.
• Answer-then-search. Many people read an AI answer, then search your brand on Google or type your address. GA4 credits organic or direct, not the assistant.
• No click at all. If the answer names you and the user calls, visits your store or buys later, no session is recorded.
• Bots aren't users. AI crawlers and user-triggered fetchers such as ChatGPT-User request pages from servers. GA4's JavaScript tag usually doesn't record them, so check server or CDN logs for those, and see AI crawlers and robots.txt.

Traffic tells you what happened after a click. Visibility tells you whether ChatGPT, Google AI Overviews, Google AI Mode, Gemini, Perplexity and Claude mention you when buyers ask about your category, which is the upstream cause. Track both: GA4 for visits and conversions, and a visibility measure for mentions and share of voice.

Glossy Data's paid plans track mentions weekly with a sample size and a 90% range on every number, so you can tell real movement from noise; see the Honest Score. A GA4 connector that puts AI visibility next to AI referral sessions is coming soon; check integrations for status. To compare yourself with rivals, read the guide to AI share of voice.