The essentials
- The principle: clicks from ChatGPT, Perplexity, Copilot, Gemini or Claude arrive in GA4 as "referral" traffic with the assistant's domain as the source; you just have to group them.
- The method: a custom channel group with a rule on the source (a regex of the AI domains), placed before "Referral".
- What stays invisible: Google's AI Overviews (counted as organic), answers with no click, mobile apps that hide the referrer.
- 2026 orders of magnitude: 0.5 to 3% of sessions for a B2B or media site, growing fast, often with a higher conversion rate than organic.
AI assistants send traffic to the sites they cite: ChatGPT with web search, Perplexity, Copilot, Gemini, Claude. In GA4, those visits exist but hide inside the "Referral" channel, mixed in with directories and partners. This article explains how to isolate them, how to read them, and what GA4 can't measure. It is the analytics counterpart to the visibility tracking described in tracking your visibility on ChatGPT and Perplexity.
The sources to recognise
| Assistant | Source in GA4 (referrer) | Notes |
|---|---|---|
| ChatGPT | chatgpt.com, chat.openai.com | Sometimes adds utm_source=chatgpt.com to links, which creates an explicit source |
| Perplexity | perplexity.ai | A stable referrer |
| Copilot (Microsoft) | copilot.microsoft.com, bing.com (chat mode) | Some of it arrives as bing.com, indistinguishable from Bing search |
| Gemini | gemini.google.com | Referrer present; the AI Overviews in Google search stay under "google / organic" |
| Claude | claude.ai | Low volume but qualified |
| Mistral (Le Chat) | chat.mistral.ai | Growing in France |
| Meta AI, Grok, DeepSeek, You.com | meta.ai, grok.com, x.com (through Grok), chat.deepseek.com, you.com | Marginal, worth including in the regex |
Mobile apps and some interfaces pass no referrer: the visit then arrives as "Direct". Measured AI traffic is therefore a floor.
Creating an "AI" channel in GA4
- Admin, Data settings, Channel groups, then "Create channel group" (or edit a copy of the default group: the default group can't be changed).
- "Add channel", name it "AI", condition: Source matches the regular expression
.*(chatgpt|openai|perplexity|copilot\.microsoft|gemini\.google|claude\.ai|mistral\.ai|meta\.ai|grok|deepseek|you\.com).* - Put this channel above "Referral" and "Organic Search" in the rule order: GA4 assigns the first channel whose condition is true.
- Save; the group applies to data from its creation onwards (it isn't retroactive) and becomes selectable in the acquisition reports as a primary dimension.
For history, use an exploration: the "Session source" dimension, the same regex filter, over the period you want. Creating explorations is described in creating a custom GA4 report.
Reading the results
| Question | Report | What you look at |
|---|---|---|
| How many visits come from AI? | Traffic acquisition, custom channel group | AI channel sessions, share of the total, monthly trend |
| Which assistant sends the most? | The same report, with "Session source" as a secondary dimension | The chatgpt / perplexity / copilot split |
| Which pages are cited? | Landing pages, filtered on the AI channel | The pages receiving the clicks: those are your cited content |
| Does this traffic convert? | Traffic acquisition, key events and rate columns | Compare with the organic channel; AI often converts better |
| Who are these visitors? | Explorations, segments | New vs returning, devices, countries |
The metrics to keep for a dashboard: AI sessions, share of traffic, cited landing pages, key events and rate by assistant. Connect them to the citations measured on the assistant side to read the whole chain, as described in GEO KPIs and GA4 and Search Console for measuring GEO.
What GA4 doesn't see
- Google's AI Overviews and AI Mode: the clicks arrive as "google / organic", indistinguishable from classic search. Only rank tracking tools detect the presence of an overview and the sources cited.
- Answers with no click: a citation read but not clicked doesn't exist in GA4. Visibility is measured on the assistant side.
- Visits with no referrer: mobile apps, copied links, some browsers; they fall into "Direct".
- The AI crawlers: GPTBot, PerplexityBot and ClaudeBot don't execute GA4's JavaScript; their visits are in the server logs, not in GA4. The subject is covered in indexing by AI.
Going further
Add an annotation on the date you created the channel so you can read the curves. Every quarter, compare the list of AI landing pages with your most-cited pages in GEO tracking tools: the gaps reveal content cited without clicks (to be reinforced with a call to action) or clicked without a detected citation (assistants not covered). Finally, mark your key events and look at the rate by channel: in most 2025-2026 measurements, visitors from assistants convert 1.5 to 3 times better than average, because they arrive with an already qualified intent.
How GreenRed helps
Rather than juggling several tools, GreenRed's GEO tracking brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Does traffic from ChatGPT appear in GA4?
Yes, when the user clicks a cited link: the session arrives with the source chatgpt.com (or chat.openai.com) in the Referral channel, sometimes with a utm_source=chatgpt.com parameter. A custom channel group lets you isolate it in an "AI" channel.
Why isn't traffic from Google's AI Overviews identifiable?
Clicks from an AI Overview or AI Mode start from the Google results page, with the same referrer as classic search. GA4 classes them as google / organic. Only rank tracking tools flag the presence of an overview on a query and the sources cited.
Does the custom channel apply to past data?
No, a custom channel group applies from its creation. To analyse history, use an exploration with a filter on session source (a regular expression of the AI domains), which works across the whole retained period.
What share of traffic comes from AI in 2026?
Between 0.5 and 3% of sessions for most B2B, media and e-commerce sites, growing by tens of percent per quarter. The share is higher on reference content (guides, definitions, comparisons) and close to zero on local transactional pages.