How to Track ChatGPT, Perplexity and Claude Traffic in GA4

What does GA4's AI Assistant channel count?

GA4's AI Assistant channel counts sessions whose medium is ai-assistant, which GA4 sets when it recognises the referrer as an AI assistant. Google added it on 13 May 2026, according to the GA4 release notes, which named ChatGPT, Gemini and Claude. When the referrer matches, GA4 sets the medium to ai-assistant and the campaign to (ai-assistant). You don't have to set anything up.

Three details on Google's own pages limit what the channel can show you:

• The named list has changed. The default channel group page now describes the channel as covering "sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok" (checked 24 October 2026). Claude and Perplexity are not named. Google doesn't publish the full list: the source list it links from that page covers search, shopping, social and video sites only.
• Google's own AI is excluded. The same page says AI Overviews and AI Mode count as Organic Search.
• It reads the referrer. A visit that arrives with no referrer gives the rule nothing to match.

The rollout was gradual. In an r/GoogleAnalytics thread from May 2026, one commenter wrote that it would reach all properties within a few weeks. In a later r/SEO thread, another commenter said it only tracks the big AI tools, not always well, and that their team still uses a regex. Itamar Blauer wrote in a Search Engine Journal guide on 15 July 2026 that it reached most properties by early June 2026. A chart that compares April with July compares two different rule sets, so start any trend line in June.

Why does one ChatGPT visit end up in different channels?

GA4 picks a channel from source and medium together, and ChatGPT visits arrive with different combinations. Google's campaigns and traffic sources page says UTM parameters in the URL set the traffic-source fields, while the referrer may fill those fields in when nothing else has set them. ChatGPT adds utm_source=chatgpt.com to many links and no medium tag.

The first three rows follow Clickport's reading of Google's rules; the Direct row is Google's own definition. The Unassigned row is the one people miss. Clickport, an analytics vendor, says in its study updated 22 October 2026 that 95% of the ChatGPT visits it identified carried the tag with no medium, in April and in October 2026. Clickport says it hasn't tested the GA4 behaviour in a property itself. Blauer's guide shows the chatgpt.com / (not set) row sitting in Unassigned, from a screenshot dated June 2026. Check your own report before you rely on either.

The bottom row is Google's own definition of Direct. Its help page on (direct) / (none) lists links without UTM parameters, redirects that strip them, typed URLs and ad blockers as causes. Referrers from AI tools are patchy too. In an Ahrefs test published 26 May 2025, Patrick Stox found a noreferrer attribute on in-content links in a paid ChatGPT account, Perplexity's desktop app didn't seem to send referrers, and Claude seemed to pass one on every link tested. Those products have changed since, so treat the test as a reason to check, and your own report as the answer.

How do you build a custom AI channel in GA4?

Build a custom channel group that matches on source and ignores medium. That folds the ai-assistant, referral and (not set) rows for each AI tool into one line. Google's custom channel groups page says groups apply to reports retroactively and that traffic goes into the first channel whose rules it matches, so the order of channels decides the result. A standard property gets two custom groups with up to 50 channels each.

1. Copy the default group

   In Admin, under Data display, click Channel groups, then Create new channel group. GA4 starts you from a copy of the default group. You need Editor access or above.

   Admin, Data display

2. Add a channel called AI tools

   Set one condition: Source, matches regex. Paste .*(chatgpt\.com|chat\.openai\.com|perplexity\.ai|claude\.ai|gemini\.google\.com|copilot\.microsoft\.com|deepseek\.com|grok\.com|meta\.ai).* and add no medium condition. The nine domains come from the 13-domain rule Clickport publishes.

   Source only, no medium

3. Move it above Referral and AI Assistant

   Click Reorder and drag AI tools above both. Google's own AI example says to put its channel above Referral.

   Order decides the channel

4. Save and switch reports to it

   In Traffic acquisition, choose your new group as the primary dimension. Old sessions regroup too.

   Works on past data

The .* at each end matters. Google's regex help page says GA4 regex is "full regex and case sensitive" by default, so a pattern has to match the whole source unless you add wildcards. Google's sample pattern on the custom channel page begins with ^.*ai, which is broad enough to catch any .ai website, assistant or not. Search Console behaves the other way: its regex filter is a partial match and not case sensitive. Don't paste a pattern from one tool into the other without testing it.

How much AI traffic does GA4 miss?

No one can give you a reliable share for your site. The published figures come from vendors' own customers and count different things:

All three are shares of AI visits the vendor could already identify. None measures how much of your Direct traffic is AI, a point the newsletter writer David Rosam makes in a September 2026 review of these numbers. Clickport also found AI visits were 0.7% of all sessions in April and 0.5% in October. Add Clickport's October groups and 74.1% of identified AI visits carried a source tag (24.4% with a referrer as well, 49.7% without). That is why a rule that matches the source, which the tag sets, catches visits a referrer-only rule would miss.

Annotate 8 to 15 October 2026 in your reports. Search Engine Journal reported on 15 October that links in ChatGPT's answer text began arriving with no tag and no referrer from around 9 October, after GPT-6 rolled out. Cedric Huesler, a senior director of product management at Adobe, said OpenAI confirmed the bug on 14 October and that a fix began rolling out on 15 October. Clicks that week could show as Direct.

Consent banners remove visits from every channel. Google's consent mode documentation says that in basic mode, when a visitor doesn't consent, nothing is sent to Google. No channel rule can sort a visit that was never sent.

How do you see which posts bring signups from AI?

Mark your signup or demo request as a key event, then read key events by landing page for the AI tools channel. Google's key events page lets a standard property mark up to 30 events as key events. In the Landing page report, add a filter for your AI tools channel and sort by key events.

Expect your homepage near the top. Similarweb reported on 25 May 2026 that after ChatGPT made brand names clickable on 7 May, about 60% of ChatGPT referrals in its clickstream panel landed on a homepage, up from roughly 26 to 32% before. A homepage visit tells you ChatGPT sent someone. It doesn't tell you which of your posts it read. Our write-up on why ChatGPT visitors land on homepages and how we rewrote ours covers that page.

For blog posts, compare two numbers each month: AI tools sessions that landed on the post, and key events from those sessions. For example, a post with 40 AI sessions and 3 signups has a 7.5% signup rate from that channel. A post with 400 sessions and 2 signups has 0.5%. The first post is the one to update and link from the homepage, even though the second looks bigger in the chart. Small counts swing a lot, so judge on three months, not one.

What should a "How did you hear about us?" field ask?

Ask in free text and sort the answers yourself. It is the only method in this guide that catches app clicks, copied links and people who saw you in an answer and typed your name later. Our guide to self-reported attribution, including how to add the field in HubSpot and Calendly, covers the setup. Copy these two fields:

Then code each answer once a week:

Keep the first question unprompted, with no examples, and show the second only after it so it doesn't steer the first answer. The second question earns its place. If several buyers write that they asked for "tools like" a named competitor, you know which comparison page to write next.

A 20-minute monthly AI traffic check

Run this on the first working day of each month:

1. In Traffic acquisition, set the dimension to Session source / medium, search for chatgpt, and add up every row. Repeat for perplexity and claude.
2. Switch to your AI tools group and note sessions and key events.
3. Put the month's self-reported AI answers next to those numbers. If buyers name ChatGPT more often than GA4 does, the rest are probably sitting in Direct, or never clicked at all.
4. Look in Referral for any AI tool you haven't listed, and add its domain to the regex.
5. If AI sessions fall only in the EEA and UK, check the consent banner first. That triage tip, made about GA4 traffic drops in general, comes from one poster in an r/GoogleAnalytics thread on consent rates, who says they build a consent platform.
6. For AI Overviews and AI Mode, open Search Console instead, because GA4 files them under Organic Search. Our checklist for diagnosing impressions without clicks in Search Console covers that side.

Before you spend more time on AI search, read our breakdown of whether ChatGPT traffic is worth chasing when Google sends far more. If the posts that win signups turn out to be comparisons and how-tos, Siela's SEO Blog Writer checks search volume, cost per click and the top 10 Google results before it drafts, and you approve the outline first.

Frequently asked questions

Sources

1. Google Analytics Help: What's new in Google Analytics (13 May 2026 entry) (checked 24 Oct 2026)
2. Google Analytics Help: Default channel group (checked 24 Oct 2026)
3. Google Analytics Help: Custom channel groups (checked 24 Oct 2026)
4. Google Analytics Help: About regular expressions (regex) (checked 24 Oct 2026)
5. Google Analytics Help: Campaigns and traffic sources (checked 24 Oct 2026)
6. Google Analytics Help: Understand (direct) / (none) traffic (checked 24 Oct 2026)
7. Google Analytics Help: Mark events as key events (checked 24 Oct 2026)
8. Search Console Help: Performance report advanced filtering and comparison (checked 24 Oct 2026)
9. Google for Developers: Consent mode overview (last updated 30 Jul 2026)
10. Clickport: Why ChatGPT Traffic Shows as Direct in GA4 (2026) (updated 22 Oct 2026)
11. Loamly: The AI Traffic Attribution Crisis (Marco Di Cesare) (published 7 Nov 2025, updated Feb 2026)
12. Search Engine Journal: How To Track AI Traffic In GA4 Without Undercounting It (Itamar Blauer) (15 Jul 2026)
13. Search Engine Journal: ChatGPT Traffic Drop Appears To Be A Tracking Problem (Matt G. Southern) (15 Oct 2026)
14. Ahrefs: AI Assistants Are Breaking Web Analytics and Hurting Their Future (Patrick Stox) (26 May 2025)
15. David Rosam: Everyone quotes 60%. Nobody measured it. (11 Sep 2026)
16. Similarweb: ChatGPT Referral Traffic Near Triples Overnight (Adelle Kehoe) (25 May 2026)
17. Search Console Help: Generative AI performance report (Search) (checked 24 Oct 2026)
18. r/GoogleAnalytics: GA4 just made AI traffic tracking easier! (May 2026, checked 24 Oct 2026)
19. r/SEO: GA4 now Reports LLM = AI Assistant Traffic (July 2026, checked 24 Oct 2026)
20. r/GoogleAnalytics: Your GA4 traffic probably did not drop, your consent rate did (Sep 2026, checked 24 Oct 2026)