ChatGPT and AI traffic in GA4: the complete setup
How to use GA4’s new AI Assistant channel, build a custom channel that also catches Perplexity and Claude, and report AI conversions. Free, about 15 minutes.
Step 1: check the built-in AI Assistant channel
In May 2026 Google added an AI Assistant channel to GA4’s default channel group. When a visit arrives from a recognised AI assistant, GA4 sets the medium to ai-assistant and groups it there. Google’s documentation names ChatGPT, Gemini, DeepSeek, Copilot and Grok, and says Google’s own AI Overviews and AI Mode are excluded.
- Open Reports → Acquisition → Traffic acquisition.
- Keep the default dimension, Session primary channel group (Default channel group), and find the AI Assistant row.
- Click the + next to the dimension and add Session source to see which assistant each visit came from.
Two things to know. The channel isn’t retroactive, so visits before the rollout stay in Referral. And check where perplexity.ai and claude.ai land in your own property: if they show under Referral, Step 2 fixes it.
Step 2: build a custom AI channel that catches every assistant
A custom channel group lets you define “AI” yourself and apply it to older data in reports.
- Go to Admin → Data display → Channel groups and click Create new channel group.
- Name it “Channels with AI”. Click Add new channel and call it AI assistants.
- Set the condition to Source matches regex and paste:
chatgpt\.com|chat\.openai\.com|gemini\.google\.com|bard\.google\.com|perplexity\.ai|claude\.ai|copilot\.microsoft\.com|copilot\.cloud\.microsoft|meta\.ai|grok\.com|chat\.deepseek\.com|chat\.mistral\.ai|you\.com|phind\.com|poe\.com- Add an OR condition: Medium exactly matches
ai-assistant. - Click Reorder and drag AI assistants above Referral. Channels are evaluated top to bottom, so if Referral comes first it swallows the AI visits.
- Save. In Traffic acquisition, switch the dimension to Session channel group → Channels with AI.
Want only some assistants, or the version for Tag Manager or Looker Studio? Use the AI referral regex generator. It uses the same referrer list as Which AI Sent.
Step 3: report AI conversions
- Make sure your form submits or purchases are marked as key events (Admin → Data display → Events → toggle Mark as key event).
- In Traffic acquisition, the Key events and Session key event rate columns now show AI conversions next to every other channel.
- For a landing-page view, build an Exploration with Session source, Landing page + query string, Sessions and Key events, filtered to your AI channel.
What GA4 still can’t tell you
| Question | GA4 |
|---|---|
| How many visits came from ChatGPT? | Yes, for visits that arrive with a referrer or UTM |
| Which of those visitors became customers, and what did they pay? | Only if every sale is sent back into GA4 |
| People who asked ChatGPT, then Googled us or phoned | No: counted as Google, or not at all |
| ChatGPT app visits with no referrer | No: counted as Direct |
| Google AI Overviews and AI Mode | No: counted as Google organic |
That gap is why AI search attribution exists. Which AI Sent follows AI visitors to the form, the booking and the sale, and asks the customers analytics can’t see. The side-by-side is in Which AI Sent vs GA4. The ChatGPT-specific picture is in how to track ChatGPT traffic.
GA4 and AI traffic
Where is ChatGPT traffic in GA4?
In Reports → Acquisition → Traffic acquisition, under the AI Assistant channel (since May 2026). Switch the dimension to Session source to see chatgpt.com on its own.
Why is Perplexity under Referral?
Google’s AI Assistant channel may not recognise every assistant. Build a custom channel group with the regex above and place it above Referral.
Does a custom channel group change my historical data?
No data is changed. Custom channel groups are applied when reports are shown, so you can see older visits grouped your way.
Can GA4 track AI Overviews?
No. Google records AI Overviews and AI Mode clicks as ordinary organic search, and the AI Assistant channel excludes them.
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