GA4 AI traffic got easier to see in May 2026, when Google Analytics added a built-in AI Assistant channel. It did not get complete. This post shows what the channel counts, how to build a custom channel that catches more with a regex that does not overcount, and the AI referral traffic that Google Analytics still cannot see at all.
GA4’s built-in AI Assistant channel
Google’s release notes for 13 May 2026 announced “a new AI Assistant channel in your Default Channel Group reports”[1]. Google defines it as the channel by which users arrive “from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok”, and says it excludes Google’s AI Overviews and AI Mode[2]. The rule is simple: when the referrer matches a list of AI assistants, GA4 sets the medium to ai-assistant and the campaign to (ai-assistant), and the channel is every session with that medium[2].
Three things follow from that definition:
- Google does not publish the list. Perplexity and Claude are not among the names in the channel definition, so check where they land in your own data.
- It depends on a referrer. A visit that arrives without one never reaches the list.
- Google’s own AI answers are elsewhere. Organic Search explicitly includes AI Overviews and AI Mode[2].
| Default channel | Can you separate it? | |
|---|---|---|
| ChatGPT with a referrer | AI Assistant | ✓Yes |
| Gemini, Copilot, DeepSeek, Grok | AI Assistant | ✓Yes |
| Perplexity, Claude | Check your data: AI Assistant or Referral | ✓Yes |
| Tagged with utm_source only | Can land in Unassigned | ~ |
| AI app with no referrer | Direct | ✕No |
| Google AI Overviews and AI Mode | Organic Search | ✕No |
ChatGPT referral traffic, and the UTM wrinkle
ChatGPT referral traffic has one extra quirk. OpenAI says ChatGPT automatically adds utm_source=chatgpt.com to the links it sends people through[4]. That helps: the source survives even when the referrer does not. But practitioners report that when a link carries a source and no medium, GA4 takes the source from the UTM and leaves the medium unset, so the session can fall into Unassigned instead of AI Assistant[7]. A custom channel that matches on source, not medium, catches those visits either way.
A regex for AI traffic in Google Analytics
Google’s help page on custom channel groups includes an example for AI assistants, with a regex whose first alternative is ^.*ai[3]. That matches any source containing the letters “ai”, including mail.google.com and any campaign tagged with an email source, so it overcounts. The builder below produces a regex that matches whole hostnames only, from a list of 12 assistants. Test any source against it, and against the loose pattern.
^([a-z0-9-]+\.)*(chatgpt\.com|chat\.openai\.com|perplexity\.ai|gemini\.google\.com|bard\.google\.com|claude\.ai|copilot\.microsoft\.com|deepseek\.com|grok\.com|meta\.ai|you\.com|mistral\.ai|phind\.com|poe\.com)$
Build an AI traffic channel in GA4
A custom channel group changes how your reports are grouped without touching the data. Standard properties can have two custom groups alongside the default one, each with up to 50 channels, and they apply to past data as well[3].
The rule-order and retroactivity details are from Google’s custom channel groups page[3].
The AI traffic Google Analytics cannot see
However good the channel, some AI referral traffic is invisible in GA4, and it is worth saying how before anyone reads the number as a total.
Search Console now has a Generative AI performance report for impressions in Google’s AI features[5], which covers part of the gap on Google’s side. For scale on the other side: across 74,752 sites in Ahrefs’ March 2026 data, AI assistants sent about 3.5 million visits, most of them from ChatGPT[6].
How CoreCited reads AI referrals from GA4
If you would rather not maintain a channel group, CoreCited connects to your GA4 property read-only, classifies sessions by assistant with the same host list as the builder above, and records the first day each assistant sent you traffic. It shows AI referrals next to AI crawler activity and the crawl-to-refer ratio in AI traffic analytics, from the Starter plan. The numbers are labelled as a floor, for all the reasons above.
Questions people ask
Does GA4 track AI traffic?
Yes, since 13 May 2026. GA4's default channel group has an AI Assistant channel for visits from assistants such as ChatGPT, Gemini, DeepSeek, Copilot and Grok. It excludes Google's AI Overviews and AI Mode, which stay in Organic Search, and it misses visits that arrive with no referrer.
How do I see ChatGPT traffic in Google Analytics?
For Google Analytics ChatGPT data, open Reports, Acquisition, Traffic acquisition, and set the primary dimension to Session source. Look for chatgpt.com, and chat.openai.com for older data. Or look at the AI Assistant channel in the default channel group. For a lasting view, create a custom channel group with the regex from the builder in this post.
Why is my ChatGPT referral traffic so low in GA4?
Because much of it is not labelled. Some AI apps open links without passing a referrer, so those visits land in Direct, and a link tagged with a source but no medium can end up in Unassigned. Every AI referral number in GA4 is a floor.
Can GA4 show traffic from Google AI Overviews or AI Mode?
No. Google puts clicks from AI Overviews and AI Mode in Organic Search, and GA4 cannot separate them. Search Console's Generative AI report shows AI impressions, but not separate clicks.
Is Perplexity in GA4's AI Assistant channel?
Google's definition names ChatGPT, Gemini, DeepSeek, Copilot and Grok as examples and says the channel uses a list of AI assistants it does not publish. Check your own Traffic acquisition report: if perplexity.ai shows under Referral, a custom channel group will catch it.
What regex should I use for AI traffic in GA4?
One that matches whole hostnames, like the one the builder in this post produces. Avoid patterns that match any source containing 'ai' or 'gpt', including the first part of Google's own sample, because they also catch sources like mail.google.com.
Is the custom channel group retroactive?
Yes. Google says custom channel groups can be applied to your reports retroactively, so the new channel works on past data too. Audiences built on them only change going forward.