What is AI referral traffic and how do you measure it?

"AI traffic" gets used for two things that are worth separating from the start. One is the people who reach your store from an assistant's answer: someone asks ChatGPT which backpack to buy, sees a link to your product page and clicks it. The other is the bots from AI companies that request your pages to read them, index them or answer a question, and leave their trace in the server logs. This entry is about the first, referral traffic; the second belongs to the crawler and to each agent. For a store, AI referral traffic is the part of its presence in answers that turns into a visit it can see.

How it works

Your analytics does not know where a visit came from: it infers it. For AI referral traffic there are two clues, and either can be missing.

The referrer. When someone clicks a link, the browser can send the address it came from in the Referer header. With the default policy, on a hop between two HTTPS sites only the origin is sent, the domain without the path; with the no-referrer policy, or with a link marked rel="noreferrer", nothing is sent.⁠^{[1]MDN Web Docs. Referrer-Policy header} At best, your store knows which assistant the visit came from, never which conversation.

The channel. Since May 13, 2026, Google Analytics has a channel of its own for these visits. When the referrer matches an AI assistant it recognizes, it assigns the visit the medium ai-assistant and the campaign (ai-assistant), and groups it in the AI Assistant channel; Google gives ChatGPT, Gemini and Claude as examples.⁠^{[2]Google Analytics Help. What's new in Google Analytics} The channel definition in its help also names Deepseek, Copilot and Grok.⁠^{[3]Google Analytics Help. [GA4] Default channel group} On June 11, 2026 it also added a source group field that, among other things, groups the different source values of sources like ChatGPT (OpenAI) and Perplexity.⁠^{[2]Google Analytics Help. What's new in Google Analytics}

What falls outside the channel. The AI Assistant channel expressly excludes AI Overviews and AI Mode, which Google Analytics counts as organic search.⁠^{[3]Google Analytics Help. [GA4] Default channel group} In Search Console, clicks from those two features are also mixed in with the rest, inside the web search type of the performance report.⁠^{[4]Google Search Central. AI features and your website} And a visit that arrives with no referrer and no campaign tags ends up as (direct) / (none), the traffic that, according to Google, has no clear referral source; among the causes it lists are links without utm_ parameters, redirects that strip them, link shorteners and ad blockers.⁠^{[5]Google Analytics Help. [GA4] Understand (direct) / (none) traffic}

What is not AI referral traffic. The agents of AI companies also visit your site, but they are not customers. OpenAI uses ChatGPT-User for some actions a person starts in ChatGPT, and warns that robots.txt rules may not apply to those requests.⁠^{[6]OpenAI. Overview of OpenAI Crawlers} Perplexity-User visits a page when someone asks Perplexity something, to answer and maybe link it, and generally ignores robots.txt.⁠^{[7]Perplexity. Perplexity Crawlers} Those requests are identified by their own user agent and are read in the server logs. Google Analytics, for its part, automatically excludes known bot traffic, using its own list and the IAB's, with no option to turn it off and no way to see how much it excluded.⁠^{[8]Google Analytics Help. [GA4] Known bot-traffic exclusion}

For all those reasons, AI referral traffic has no standard definition. The AI Assistant channel is Google Analytics' definition, with its list of assistants and its exclusions; another analytics tool may count other sources, and none of them sees the visits that arrive without a trace.

In a store

Five ways an AI answer can bring someone, or something, to the same product page of a backpack store, and where each one ends up. It is a fictional example: the domains are made up, and the result in each row follows Google Analytics' published rules.⁠^{[3]Google Analytics Help. [GA4] Default channel group}⁠^{[5]Google Analytics Help. [GA4] Understand (direct) / (none) traffic}

Only the first row ends up in the AI Assistant channel, and all five start in an AI answer. That is why the channel's figure is a minimum, not the total. The last row, by contrast, should never be added in: it is a machine reading the page, even if a person asking a question stands behind it.

How to check it

1. Open traffic acquisition in Google Analytics by default channel group and find the AI Assistant row, with dates after May 13, 2026.⁠^{[2]Google Analytics Help. What's new in Google Analytics}
2. Break it down by source to see which assistants the visits come from, and by landing page to see which product pages get that traffic.⁠^{[2]Google Analytics Help. What's new in Google Analytics}
3. For Google's AI, go to Search Console: clicks from AI Overviews and AI Mode are in the performance report, inside the web search type.⁠^{[4]Google Search Central. AI features and your website} The generative AI performance report gives their impressions, not their clicks.
4. Separate the bots in the server logs. Filter by the user agents each company documents, such as ChatGPT-User or Perplexity-User, and verify the IPs: Perplexity publishes its ranges as JSON files.⁠^{[6]OpenAI. Overview of OpenAI Crawlers}⁠^{[7]Perplexity. Perplexity Crawlers} Those lines are not customer visits.
5. Look at which deep product pages get a lot of direct traffic. A long URL nobody would type by hand is a clue of lost referrers, not proof.⁠^{[5]Google Analytics Help. [GA4] Understand (direct) / (none) traffic}

Related concept: LLM attribution

AI referral traffic counts visits; attribution takes the next step: it ties those visits to the orders they produce and says honestly which part cannot be attributed. You can have hundreds of visits from assistants and no orders, or orders that started in an AI answer and arrived as direct. Traffic says how many arrive; attribution says what they buy and what you cannot see. And before both comes AI visibility: whether you show up in the answers in the first place.

To keep going, the measurement and verification reading path orders the rest of the terms, and the entry on assisted conversion explains how credit is split when a sale passes through several channels.