How to Track AI Search Referral Traffic in GA4
Amit Malvi
Founder, SearchAxe. Former Senior SEO Manager, Invideo AI
Published Updated 11 min read
Quick answer
To track AI search referral traffic in GA4, start with the AI Assistant channel Google added to the default channel group on May 13, 2026. Then build a custom channel group with a regex that names each assistant's referrer, place it above Referral, and report signups and demo requests by that channel. Clicks from Google AI Overviews and Google AI Mode stay inside Organic Search, and some AI visits arrive as Direct.
On this page
- Does GA4 track AI search referral traffic on its own?
- Which referrer sources identify each AI engine?
- How do you track AI search referral traffic in GA4 with a custom channel group?
- What AI traffic can GA4 not see?
- How do you tie AI referrals to signups and pipeline?
- What should a monthly AI traffic report include?
Key takeaways
- GA4 now labels visits from recognised AI assistants with the medium ai-assistant and groups them in a default AI Assistant channel, but Google has not published the full list of assistants.
- A custom channel group with your own regex shows exactly which sources count, applies to past data, and catches visits whatever medium GA4 records.
- Do not copy Google's example regex as is, because its first pattern matches every source ending in ai, which for an AI startup includes partner and customer sites on .ai domains.
- Clicks from Google AI Overviews and Google AI Mode are counted as Organic Search, and visits from apps that drop the referrer land in Direct.
- Judge AI referrals by key events and pipeline per source, not sessions, because the volumes are small.
You track AI search referral traffic in GA4 with two layers: the AI Assistant channel Google now applies automatically, and a custom channel group you control. If you run growth at an AI startup and signups have started mentioning ChatGPT in a how-did-you-hear field, this guide gets those visits into a report your board can read. The default channel alone is not enough, because Google has not published which assistants it recognises, and clicks from Google AI Overviews and Google AI Mode never reach it.
Does GA4 track AI search referral traffic on its own?
Partly. Since May 13, 2026, according to Google Analytics' What's new page, GA4 sets the medium to ai-assistant and the campaign to (ai-assistant) when the referrer matches a recognised AI assistant, and groups those sessions in a new AI Assistant channel. Google names ChatGPT, Claude and Gemini as examples there, and its default channel group definitions give ChatGPT, Gemini, Deepseek, Copilot and Grok as examples.
Three gaps remain. Google has not published the full list of assistants it recognises, so you cannot be sure Perplexity or a new assistant is included. The same definitions page says the AI Assistant channel excludes Google AI Overviews and Google AI Mode, which are counted as Organic Search. And we have not seen Google document whether visits before May 13, 2026 were reclassified, so check a date range from earlier in the year in your own property. A custom channel group closes the first and third gaps.
Which referrer sources identify each AI engine?
Each assistant arrives with its own source value in the Session source dimension. Open Reports, then Acquisition, then Traffic acquisition, switch the primary dimension to Session source, and search for the values below to confirm the exact strings in your property before you write any rules.
| Engine | Session source to look for | Notes |
|---|---|---|
| ChatGPT | chatgpt.com | OpenAI's publisher FAQ says ChatGPT adds utm_source=chatgpt.com to referral URLs from ChatGPT search, so the source survives even when a referrer is stripped |
| Perplexity | perplexity.ai | Not named in Google's AI Assistant examples, so confirm where it lands |
| Claude | claude.ai | Named in Google's May 2026 announcement |
| Gemini | gemini.google.com | The Gemini app is separate from Google Search |
| Google AI Overviews and Google AI Mode | google, medium organic | Counted as Organic Search in GA4; clicks sit inside Search Console's Web search type, and impressions appear in Search Console's Generative AI performance report |
| Copilot | copilot.microsoft.com | Bing Webmaster Tools' AI Performance report counts Copilot citations, which GA4 cannot see |
OpenAI's wording is in its publishers and developers FAQ: sites that allow OAI-SearchBot can track ChatGPT referrals in tools such as Google Analytics because of that UTM parameter. For Google's AI features, Google Search Central confirms that sites appearing in Google AI Overviews and Google AI Mode are included in Search Console's overall search traffic, in the Performance report under the Web search type.
Find out which AI engines recommend you
A free consultation on where you appear today across AI engines and search.
Schedule a Free ConsultationHow do you track AI search referral traffic in GA4 with a custom channel group?
Copy the default channel group, add an AI channel that matches both GA4's ai-assistant medium and your own list of assistant sources, and move it above Referral. Google's custom channel group documentation covers the menus, and the steps below add the choices that matter for an AI startup. You need the Editor role or above on the property.
Set up an AI channel in GA4
- Open Admin, then Data display, then Channel groupsStandard GA4 properties allow two custom channel groups with up to 50 channels each, so name this one clearly, for example Channels with AI.
- Click Create new channel groupGA4 starts you from a copy of the default group, so every existing channel keeps working and you only add one.
- Add a channel called AI assistantsSet the first condition to Medium exactly matches ai-assistant, then add an OR condition of Source matches regex with the pattern below, so the channel catches GA4's own label and the sources you name.
- Reorder so AI assistants sits above ReferralGoogle's documentation says traffic goes into the first channel whose definition it matches, so a channel below Referral would never receive these visits.
- Save the group and open Traffic acquisitionCustom channel groups apply to reports retroactively, so you can compare AI visits before and after May 13, 2026 straight away.
- Mark signups and demo requests as key eventsWithout key events you can count AI visits but not what they are worth, which is the question your CFO will ask.
- Recheck sources every quarterAssistants change domains and new ones appear, and Google itself says you should update the regex when URLs or assistants change.
.*(chatgpt\.com|openai\.com|perplexity\.ai|claude\.ai|gemini\.google\.com|copilot\.microsoft\.com).*The leading and trailing .* make the pattern behave the same whether GA4 treats the condition as a full or partial match, and the escaped dots stop chatgptXcom-style lookalikes from matching. Add a source only after you have seen it in your own Session source report.
Why not copy Google's example regex
Google's example in the same help article begins with ^.*ai| and includes .gpt.. If GA4 applies the pattern as a full match, ^.*ai matches every source ending in ai. If it applies a partial match, it matches any source containing those two letters, such as mail.yahoo.com. Either way, for an AI startup whose partners, customers and review sites often sit on .ai domains, ordinary referrals get counted as AI assistant traffic, and .gpt. does the same to any site with gpt in its name.
What AI traffic can GA4 not see?
GA4 misses AI influence that does not arrive as a tagged click. Google AI Overviews and Google AI Mode clicks sit in Organic Search. Visits from apps or browsers that drop the referrer land in Direct. And buyers who read an answer, then type your URL or search your brand on Google or Bing later, show up as Direct or branded organic.
Watch five proxy signals beside the AI channel: Direct sessions landing on the homepage, branded query impressions in Google Search Console and Bing Webmaster Tools, impressions in Search Console's Generative AI performance report, Copilot citations in the Bing Webmaster Tools AI Performance report, and a required how-did-you-hear field on signup that lists each engine by name. None of these proves causation alone. Moving together over a quarter, they tell you more than the AI channel does on its own.
How do you tie AI referrals to signups and pipeline?
Report key events by your AI channel in GA4, then carry the source into your CRM so you can see pipeline, not only signups. GA4 answers how many AI visits became signups. Only the CRM answers whether those signups became revenue.
- In Explore, build a free-form exploration with your custom channel group and Session source as rows, and Sessions, Key events and Session key event rate as values, filtered to your signup event.
- Add a second view using the first-user version of your custom channel group, which shows the channel that first brought each user, including users who signed up on a later visit.
- Capture utm_source and the referrer in hidden fields on signup and demo forms, and store them on the lead record so sales stages and revenue can be grouped by AI source.
- Compare against Organic Search for the same landing pages, because ChatGPT visits now skew towards the homepage, and a homepage converts differently from a blog post.
Expect small numbers. In Seer Interactive's June 2025 case study of a single client, AI visits were just under 11,000 sessions against almost 14 million organic sessions over seven months. At those volumes one extra signup moves a conversion rate visibly, so read AI channel results by quarter. What the published studies say about conversion rates is in whether traffic from ChatGPT and Perplexity converts better than Google traffic.
What should a monthly AI traffic report include?
A monthly report should put AI referral outcomes next to the visibility that drives them, so a change in one can be checked against the other. Keep it to one page, the same metrics every month, measured against the baseline.
| Metric | Where it comes from | Why it is on the page |
|---|---|---|
| AI assistant sessions by source | GA4 custom channel group | Shows which engines send visits and whether volume is growing |
| Signups and demo requests from AI sources | GA4 key events, checked against the CRM | The outcome that justifies spend |
| AI share of sessions versus share of signups | GA4 | Shows whether AI visitors convert above or below average for your site |
| Pipeline and revenue by first AI source | CRM, from hidden form fields | The only line a board cares about over time |
| Google AI Overviews and Google AI Mode impressions | Search Console Generative AI performance report | First-party Google visibility GA4 cannot see |
| Copilot citations and cited pages | Bing Webmaster Tools AI Performance | A free visibility signal GA4 cannot see |
| Share of voice on the frozen prompt set | Your tracker or manual check | Visibility that should lead referral changes |
The share of voice line is explained in what share of voice in AI search is and how to calculate it, and the difference between visibility and rankings in what AI visibility means and how it differs from search rankings. This reporting layer is the part of AI visibility work that turns citations into a number finance will accept.
Frequently asked questions
Does GA4 show Google AI Overviews and Google AI Mode traffic separately?
No. Google's default channel definitions count clicks from Google AI Overviews and Google AI Mode as Organic Search, and the AI Assistant channel explicitly excludes them. Clicks stay inside Search Console's Web search type, but the Generative AI performance report, available to all sites since August 31, 2026, shows impressions in both features by page, country, device and date. Use it beside a manual or tool-based check of which pages these features cite.
Why does some ChatGPT traffic show up as Direct in GA4?
Visits arrive as Direct when the browser or app does not pass a referrer and the link carries no UTM parameter. OpenAI says ChatGPT search adds utm_source=chatgpt.com to referral links, which helps, but people also copy a brand name from an answer and type the URL themselves. Similarweb reported that most ChatGPT referrals now land on homepages, so watch homepage Direct sessions as a proxy.
Does the GA4 AI Assistant channel include Perplexity?
Google has not published the full list of assistants the channel recognises. Its examples name ChatGPT, Claude, Gemini, Copilot, Grok and Deepseek. Perplexity is not among them. To check, open Traffic acquisition with the default channel group, filter to AI Assistant and add Session source as a secondary dimension. A custom channel group with perplexity.ai in its regex removes the doubt either way.
Do GA4 custom channel groups work on historical data?
Yes. Google's documentation says custom channel groups can be applied to reports retroactively, so a group you create today reclassifies earlier sessions in Acquisition reports and explorations. The exception is the primary channel group setting: if you make a custom group your property's primary channel group, the new rules populate that dimension only from that point forward, so keep the custom group itself for historical comparisons.
What regex should I use for AI traffic in GA4?
Use a pattern that names each assistant's domain with escaped dots, wrapped in .* so it behaves the same under full or partial matching. A starting point covers chatgpt.com, openai.com, perplexity.ai, claude.ai, gemini.google.com and copilot.microsoft.com. Add a source only after you see it in your own Session source report, and avoid broad patterns such as .*ai or .*gpt.*, which catch ordinary referral sites.
