ChatGPT 
Claude 
To check AI traffic in GA4, open Reports, Acquisition, Traffic acquisition and look for the AI Assistant row in Session default channel group; it covers recognized AI platforms from May 13, 2026. For earlier data and unlisted tools, add a custom channel group with a regex on Source. Treat both as a floor: AI clicks without a referrer still land in Direct.
If your Traffic acquisition report shows almost no sessions from ChatGPT, Perplexity or Gemini, your property is almost certainly undercounting. The sessions are arriving. They are being misclassified as Direct or absorbed into an undifferentiated Referral pile, invisible in every report you run.
There are two methods for checking AI traffic in Google Analytics 4 (GA4). The first is a native channel Google added in May 2026 that works with zero configuration. The second is a custom channel group you build yourself with a regex filter: it covers historical data the native channel cannot reach and catches AI platforms Google has not yet added to its recognized list.
Use both, with accurate expectations. Even with both running, a large share of AI-referred sessions arrive with no referrer header and land in Direct. The two methods together give you a floor. The real number is higher.
| Method 1AI Assistant channel | Method 2Custom channel group | |
|---|---|---|
| Setup | None, on by default | Nine steps in Admin, Channel groups |
| Data range | From May 13, 2026 only | Your full property history |
| Platforms covered | Google's recognized list | Any source your regex names |
| Who maintains it | You, as new AI tools appear | |
| Clicks with no referrer | Missed, land in Direct | Missed, land in Direct |
| Best for | Ongoing monthly monitoring | History, trend reports and unlisted tools |
What is the GA4 AI Assistant channel?
The AI Assistant channel is a default channel group entry Google added to GA4 on May 13, 2026. It classifies sessions as AI Assistant when the referrer domain matches a list of recognized AI platforms. No configuration is required on your side.
AI Assistantai-assistant(ai-assistant)Before this update, sessions from chatgpt.com, perplexity.ai, claude.ai and similar platforms landed in Referral, alongside press coverage, directory listings and partner traffic, and there was no way to isolate them without a custom filter. Now, when a recognized AI platform passes a referrer on a click to your site, GA4 assigns the values above automatically.
It has one hard limit: the channel only holds data from May 13, 2026 onward. Sessions before that date are not reclassified. To see what your AI traffic looked like last year, you need Method 2.
Method 1: How to find your AI Assistant channel traffic
Go to Reports, Acquisition, Traffic acquisition. Set the primary dimension to Session default channel group and look for the AI Assistant row. If it is there, your property is receiving qualifying AI-referred sessions. No admin configuration is required.
- Open Reports from the left navigation in GA4.
- Select Acquisition, then Traffic acquisition.
- Confirm the primary dimension is set to Session default channel group.
- Scan the table for AI Assistant. No row means no qualifying sessions yet, or every AI referrer is being stripped before it reaches your site.
- Add Session source / medium as a secondary dimension. The AI Assistant row splits into platforms such as chatgpt.com and gemini.google.com, each with its own sessions and key events.
- For deeper analysis, open Explore, then Free form. Put Session default channel group in Rows, add Sessions, Engaged sessions and Key events, and filter to AI Assistant.
AI-referred visitors arrive with context: they asked an AI a question and followed a citation to your site. Compare their key event rate with other channels in that exploration, because conversion rate tells you more about this channel than session volume does.
One caveat: this method only holds data from May 13, 2026. If your property predates that, and it almost certainly does, there is a gap in AI attribution the native channel cannot fill. That is what Method 2 is for.
Method 2: Track LLM referral traffic with a custom channel group
A custom channel group in GA4 classifies sessions with a regex filter on the Source dimension. Unlike the native AI Assistant channel, it applies retroactively to all historical data in your property and catches AI platforms not yet on Google's recognized list.
This is the method you need to compare AI referral volume from six months ago with today, to prepare a stakeholder report that covers a period before May 2026, or to own a definition you can extend as new AI tools gain traction.
- In GA4, open Admin (the gear icon, bottom left).
- Under Data display, click Channel groups.
- Click Create new channel group and name it, for example AI Referral Sources.
- Click Add new channel and name the channel AI Traffic.
- Set the condition to Source matches regex.
- Paste one of the regex patterns below into the value field.
- Click Done, then drag AI Traffic to the top of the channel list. GA4 assigns each session to the first matching channel, so if Referral sits above it, chatgpt.com sessions match Referral first and never reach AI Traffic.
- Click Save group.
- Back in Traffic acquisition, pick the new channel group from the dropdown above the chart. The AI Traffic row now shows data back to the start of your property history.
^.*ai|.*\.openai.*|.*chatgpt.*|.*gemini.*|.*gpt.*|.*copilot.*|.*perplexity.*|.*google.*bard.*|.*bard.*google.*|.*bard.*chatgpt\.com|chat\.openai\.com|perplexity\.ai|claude\.ai|anthropic\.com|gemini\.google\.com|copilot\.microsoft\.com|deepseek\.com|grok\.com|meta\.ai|you\.com|poe\.comIf your property has never had a custom channel group for AI traffic, you have no historical baseline to measure against. Every month of data before today still contains those AI-referred sessions, sitting in Referral or Direct right now. Method 2 surfaces them retroactively.
What both methods together still miss
Both methods only capture sessions where the browser sends a referrer header to your site. When that header is missing, GA4 has no information about where the session came from, and it lands in Direct or (not set), whichever methods you run.
Mobile app clicks
ChatGPT, Copilot, Gemini and Perplexity all have apps. App-to-browser handoffs pass no referrer.
Copy and paste
A reader copies the cited URL into a new tab. No referrer is sent, so GA4 records Direct.
Privacy settings
Strict browser modes and extensions such as uBlock Origin or Privacy Badger strip referrers.
There is no GA4 setting that recovers these sessions. For links you control, such as newsletters, social posts and outreach emails, add UTM parameters: they override whatever the browser does with the referrer. For third-party AI citations of your content, the sessions are not recoverable from GA4 reports alone.
Treat the combined output of both methods as a lower bound on your real AI-referred traffic. Part of the missing picture sits in Search Console instead, because its Generative AI features report counts AI Overview citations that were seen, whether or not anyone clicked.
Run both methods together
Method 1 and Method 2 are not alternatives. They cover different ground.
The native AI Assistant channel needs no setup and runs automatically from May 2026 forward. Use it for ongoing monitoring: month-over-month AI traffic, key event rates by AI platform, and which tools send the most qualified visitors.
The custom channel group applies across your full property history. Use it for any analysis that spans the period before May 2026, for historical trend reports, and for AI sources Google has not yet added to its list. As new AI tools emerge, you extend the regex instead of waiting for Google to update its definitions.
Running both also surfaces something useful: the difference between what Method 2 identifies and what Method 1 labels shows which AI platforms send referrer-intact traffic Google already recognizes, and which arrive with referrers GA4 has not yet categorized.
