TutorialPractitioner3 min read

AI Referral Traffic in GA4: AI Assistant Channel and Custom Regex

Track AI referral traffic in GA4: what the AI Assistant channel covers, a copyable custom channel regex, and how to check what slips through.

Dipuck Jones
Written by Founder of MentionX · 13+ years in B2B SaaS growth and SEO
Reviewed
Short answer

GA4's default channel group now has an AI Assistant channel, but a custom channel group with a tight source regex still gives you a clearer, editable view of AI referral traffic, including past data. Build it once, place it above Referral, and compare it with the default channel monthly.

Key takeaways
  • The default AI Assistant channel covers referrers on Google's own list, such as ChatGPT, Gemini, Deepseek, Copilot and Grok.
  • Custom channel groups apply retroactively. Standard properties get 2 custom groups with up to 50 channels each.
  • Google's example regex starts with ^.*ai, which over-matches. Use the tighter regex below.
  • Put your AI channel above Referral, and above Organic Search if you want it to win ties.
  • AI traffic is undercounted either way, because apps often strip the referrer.

Checked 4 November 2026 (CET) against Google Analytics Help and Google developer documentation. GA4 menus and limits change, so confirm in your own property. "Our view" marks MentionX opinion. Ledgerline is a fictional company used for illustration.

01How do you build the custom channel group?

  1. Go to Admin → Data display → Channel groups → Create new channel group.
  2. Name it, for example "Channels with AI split". GA4 copies the default channels in.
  3. Click Add new channel, name it "AI assistants", set Source → matches regex and paste the regex below.
  4. Use Reorder to move "AI assistants" above Referral (and above Organic Search).
  5. Save. In Traffic acquisition, change the primary dimension to your new group.

02A tighter regex

^(chatgpt\.com|chat\.openai\.com|openai\.com|perplexity\.ai|www\.perplexity\.ai|gemini\.google\.com|copilot\.microsoft\.com|claude\.ai|chat\.deepseek\.com|grok\.com|meta\.ai|chat\.mistral\.ai|you\.com|poe\.com)$

If your property shows sources with paths or subdomains, use a looser end such as (chatgpt|perplexity|claude|copilot|gemini|deepseek|grok)\. and test it. Google's own example is:

^.*ai|.*\.openai.*|.*chatgpt.*|.*gemini.*|.*gpt.*|.*copilot.*|.*perplexity.*|.*google.*bard.*|.*bard.*google.*|.*bard.*|.*.*gemini.*google.*$

Because the first alternative is ^.*ai, it matches any source containing "ai", including mail.google.com and many unrelated domains. Tighten it before you rely on it.

03How do you check what slips through?

Run this monthly in a free-form exploration (lesson 9): rows = Session source, filter Session source matches regex (gpt|ai|chat|copilot|gemini|claude|perplexity) and compare with your channel. Add any genuine assistant you find to the regex and note the date. The measurement guide to GA4 custom channel groups goes deeper on regex testing, and why AI referral traffic is undercounted explains the Direct problem.

Our view: the default AI Assistant channel is the right number for trend lines because Google maintains it. Your custom group is the right one for diagnosis. Report both, labelled.

04Example: Ledgerline

Ledgerline (fictional) built the group and saw chatgpt.com, perplexity.ai and copilot.microsoft.com as separate rows, with most AI visits landing on comparison pages. That pointed its content team at comparison content rather than the blog. For assistant-specific tracking, see measuring brand visibility in Claude and Tracking ChatGPT referral traffic and mentions.

Next: Customising standard reports and the library. Or return to the GA4 for Marketers track.

05Common questions

Do I still need a custom AI channel if GA4 has AI Assistant? It is still useful. The default list isn't published in full, and a custom group lets you split assistants individually, apply your own definition and relabel past data.

Is Google's example regex safe to use? Use it with care. It starts with ^.*ai, which matches any source containing "ai", such as mail domains. A tighter list of known domains is safer.

Can GA4 see AI Overviews traffic separately? No. Google classes AI Overviews and AI Mode as Organic Search, and the referrer is google. Search Console is the place to look.

Questions people ask

3 answers

Do I still need a custom AI channel if GA4 has AI Assistant?

It is still useful. The default list isn't published in full, and a custom group lets you split assistants individually, apply your own definition and relabel past data.

Is Google's example regex safe to use?

Use it with care. It starts with ^.*ai, which matches any source containing "ai", such as mail domains. A tighter list of known domains is safer.

Can GA4 see AI Overviews traffic separately?

No. Google classes AI Overviews and AI Mode as Organic Search, and the referrer is google. Search Console is the place to look.

Sources

  1. Google Analytics Help, Custom channel groupssupport.google.com
  2. Google Analytics Help, Default channel groupsupport.google.com
  3. All accessed 4 Nov 2026.
Written and reviewed by Dipuck JonesHow we research and testReport an error

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