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How to track AI search traffic in GA4

Google Analytics 4 now has an AI Assistant channel in its default channel group, for visits from products like ChatGPT, Gemini, and Copilot. It does not include Google’s own AI Overviews or AI Mode. Those clicks count as Google search. To see the whole picture you need GA4, Search Console, and a few minutes on a custom channel group.

What GA4 does by default

The default channel group help page describes the AI Assistant channel as the way people arrive at your site from sources like ChatGPT, Gemini, DeepSeek, Copilot, or Grok. Two rules define it:

  • The medium exactly matches ai-assistant.
  • If the referrer matches a list of AI assistants, GA4 sets the medium to ai-assistant and the campaign to (ai-assistant).

Google does not publish that list on the page. The page also does not say when the channel started or whether older data was reclassified. So treat the channel as useful but not complete, and check which sources actually land in it on your property.

The same page says the AI Assistant channel excludes Google’s AI Overviews and AI Mode. That is the most important line for this guide.

Default channel definitions cannot be edited. If you want different rules, you build a custom channel group, covered below.

Where each AI source shows up

Where a click from each product is likely to land. The last column says whether that is documented or what you should check.
Source Likely channel Basis
ChatGPT AI Assistant Google names ChatGPT as an example. OpenAI’s publisher FAQ says ChatGPT adds utm_source=chatgpt.com to referral URLs.
Gemini app, Copilot AI Assistant Google names both as examples.
Perplexity, Claude Check your data Not named in Google’s description. They may be on the unpublished list, or they may land in Referral.
Google AI Overviews, AI Mode Organic Search Excluded from AI Assistant, per Google. Google’s AI features page says this traffic is counted in Search Console’s Performance report under the Web search type, with the rest of search.

Find it in your reports

In the traffic acquisition report, set the primary dimension to the session default channel group and look for AI Assistant. Then switch the dimension to session source / medium to see which sites are inside it.

Pick the scope on purpose. Google’s page on scopes of traffic-source dimensions separates them:

  • Session dimensions describe what started each session. A returning visitor who came from ChatGPT last week and from Google today is counted under Google today.
  • First user dimensions describe how a user was first acquired, and keep that value when they return.

For “how many visits did AI answers send this month,” use session. For “how many customers did we first meet through an AI answer,” use first user.

Build a custom channel group for AI

A custom channel group lets you define AI traffic your way and apply it to past data. Google’s custom channel groups page describes the steps:

  1. Create the group

    In Admin, under Data display, open Channel groups and choose Create new channel group. That makes a copy of the default group. You need Editor access or above on the property.

  2. Add an AI channel

    Add a channel, name it something like “AI answers,” and give it a condition on source, using “matches regex.” The pattern below is an example. The hostnames are ones site owners commonly see, not a list any vendor publishes. Compare it with the sources in your own report before you save.

    chatgpt\.com|perplexity\.ai|claude\.ai|gemini\.google\.com|copilot\.microsoft\.com

  3. Put it near the top

    Google says traffic goes into the first channel whose definition it matches, so order matters. If Referral sits above your AI channel, Referral will catch those visits first. Move the AI channel above Referral.

  4. Save and compare

    Google says custom channel groups apply to reports retroactively. Compare your AI channel with the built-in AI Assistant channel over the same dates. A gap tells you which sources the default list leaves out.

Limits: a standard property can have two custom channel groups besides the default, and each group can hold up to 50 channels.

A note on UTM tags

Google’s page on manual tagging says that if any UTM parameter is present, GA4 takes all of the traffic-source values from UTM parameters alone, and missing ones show as (not set). ChatGPT adds a source tag. OpenAI does not say it adds a medium tag. So some ChatGPT sessions may show chatgpt.com / (not set) rather than / referral. That is a reading of Google’s rule, not something either company states for this case. Look at your own source / medium values, and write your custom channel condition on source so the medium does not matter.

Do not try to add your own UTM tags to links you hope assistants will use. You do not control which URL an answer cites, so the tag would rarely be the one that arrives.

Google AI Overviews and AI Mode: use Search Console

Because GA4 files these clicks under Organic Search, the place to see them is Search Console.

  • The Generative AI performance report counts impressions: how many times links to your site were shown in AI Overviews or AI Mode. Google says it rolled out to all sites worldwide as of 31 August 2026. It does not include Search Labs experiments. If the report is missing, Google says the site may not have enough of those impressions, or may be excluded from these features.
  • The regular Performance report includes AI Overviews and AI Mode traffic inside the Web search type, mixed with other search clicks.

Google’s AI features page also suggests tracking conversions and time on site in tools such as Google Analytics, and says it has seen that clicks from results pages with AI Overviews tend to be higher quality. That is Google’s general observation, not a promise about your site. Your own key event rates by channel will tell you more.

For Copilot and Bing, Bing Webmaster Tools has an AI Performance report that counts citations and shows sample grounding queries. It complements GA4, which only sees the click.

Reading the numbers

Expect the AI channel to be small next to organic search for most sites, at least for now. Small is not the same as unimportant. Compare key event rates, not only session counts: sign-ups or purchases per session from the AI channel against the same rate for organic search. A small channel that converts well deserves attention. Watch the trend month over month, and remember that a custom channel group applied retroactively will change last month’s numbers too, so note the date you set it up.

What none of these tools can see

  • Mentions without a click. An answer can name you, and the reader never clicks. No analytics tool records that.
  • Later visits. Someone who reads your name in an answer and types it into Google tomorrow shows up as branded search or direct.
  • The wording. None of these reports shows what the answer said about you.

That is why the numbers are small for most sites even when AI answers mention them often. Pair the reports with the manual check, run on a schedule.

A ten-minute setup

  1. Open the traffic acquisition report and look for the AI Assistant channel.
  2. Switch to session source / medium and note which AI sources appear, and which land in Referral instead.
  3. Create a custom channel group with an AI channel above Referral, using a source regex built from your own data.
  4. Add key events by channel, so you see sign-ups and purchases, not only sessions.
  5. In Search Console, open the Generative AI performance report for AI Overviews and AI Mode impressions.
  6. If you use Bing Webmaster Tools, open the AI Performance report too.

Related: showing up in ChatGPT search, and getting cited by Perplexity.

Sources