How to Track ChatGPT and Perplexity Traffic in GA4

What GA4 sees, and what it does not

When a person clicks a link inside an AI answer, the browser sends a referrer, and GA4 records a session with source set to that referrer’s domain and medium set to referral. That part works without any setup. The problem is presentation: those sessions land in the Referral channel next to every other site that links to you, so the AI traffic never appears as a line of its own.

Two things GA4 will never see: answers read without a click (the buyer learns your name and moves on), and clicks from apps that strip the referrer. Both show up later as Direct traffic and as branded search. Measuring those belongs to the visibility and demand layers in How to measure AEO. This guide covers the traffic layer only.

Step 1: the referrer list

These are the domains to match. Update the list every quarter; engines add domains.

A single regular expression covers them:

chatgpt\.com|chat\.openai\.com|openai\.com|perplexity\.ai|gemini\.google\.com|bard\.google\.com|copilot\.microsoft\.com|bing\.com/chat|claude\.ai|meta\.ai|you\.com|phind\.com|mistral\.ai|deepseek\.com

Step 2: create the AI Assistants channel

1. In GA4, open Admin, then Data display, then Channel groups.
2. Create a new channel group (do not edit the default one; keep it as a fallback). Name it “Channels with AI”.
3. Add a channel named “AI Assistants”. Condition: Source matches regex, paste the expression above.
4. Drag the new channel to the top of the list so it takes precedence over Referral.
5. Save. Google states that custom channel groups apply to reports retroactively, so the new channel also shows past sessions from assistants, which gives you a baseline on day one. A standard property allows two custom groups of up to 50 channels each, and Google’s own help article now includes an AI assistants example (Google Analytics Help).

If your account uses the default channel group in saved reports, switch the primary dimension in those reports to the new group.

Step 3: the comparison exploration

One exploration answers the question the CEO will ask: is this traffic any good?

1. Explore, then Blank. Name it “AI Assistants vs Organic”.
2. Dimensions: Session channel group (Channels with AI), Landing page.
3. Metrics: Sessions, Engaged sessions, Average engagement time per session, Key events (your lead form and booking events), Session key event rate.
4. Rows: Session channel group. Filter: channel group exactly matches AI Assistants or Organic Search.
5. Add a second tab with Landing page as rows and the channel as a filter on AI Assistants. That tab lists the pages the engines send people to, which is the list of pages to protect and expand.

Read it monthly. The pattern to expect: fewer sessions than organic, higher engagement, a higher key event rate. If engagement is lower, the cited page does not deliver what the answer promised; fix the page, not the channel.

Step 4: make the key events count

AI traffic is small, so every conversion matters and every missed one distorts the picture.

• Mark the lead form submission and the booking click as key events (Admin, then Events, toggle the key event switch).
• If the form is on a thank-you page, create the event from the page view of that URL.
• Check that the consent banner allows analytics before the form fires; a banner that blocks GA4 until accepted hides a share of every channel, and AI visitors, arriving with intent, often submit before they touch the banner.

Step 5: the field that catches the rest

Most AI-influenced visits never click a link. Add one question to every form: “How did you hear about us?”, with “ChatGPT or another AI assistant” among the options. Report it monthly next to the GA4 channel. When self-reported AI leads outnumber AI referral sessions, which happens, that is the zero-click share showing itself.

Step 6: keep the referrers honest

Three checks, once a quarter:

• Open the Traffic acquisition report, set the dimension to Session source, and scan for new domains that look like assistants. Add them to the regex.
• Compare the AI Assistants channel with the server log count of AI agent fetches from the AEO KPI guide. Fetches rising with referrals flat means you are being read but not linked; the answer at the top of the page is not liftable enough.
• Confirm the channel still sits above Referral in the channel group order after any GA4 admin changes.

Optional: Looker Studio in five minutes

Connect GA4 to Looker Studio, add a table with Session channel group (Channels with AI) and Sessions, Engaged sessions, Key events, and filter to AI Assistants. Add a time series of the same channel. Share the link with the CEO; it is the one AEO chart most companies never build.

Frequently asked questions

Does traffic from ChatGPT show up in Google Analytics 4?

Yes, as referral from chatgpt.com or chat.openai.com when a link inside the answer is clicked. It is hidden inside the Referral channel until you create a custom channel for it.

Why is my AI traffic so small?

Because most answers are read without a click. The visibility layer (are you named and cited) and the demand layer (branded search) carry most of AEO’s effect; GA4 sees only the clicks. Small and rising is the normal shape.

Can I see which question the visitor asked?

No. Assistants do not pass the prompt. The landing page tells you which topic; the monthly visibility run tells you which questions cite that page.

Should I use UTM parameters for AI traffic?

Only on links you place yourself, for example in a PR piece you hope gets lifted. You cannot add UTMs to the links an engine chooses, so referrer matching is the reliable method.

Do Google AI Overviews clicks appear as AI traffic?

No. They arrive as google organic and cannot be separated from a normal search click in GA4. Search Console’s question-shaped queries are the closest proxy.

See the whole picture, free

GA4 covers one of AEO’s four layers. The Growth Snapshot measures the first one for you: your buyer questions in four engines, your mention and citation share against three competitors. Free for companies that fit the profile, within seven business days. See the Growth Snapshot.

Eran Regev( Founder & CEO, Growth Engines )

Eran Regev is the founder of Growth Engines and the accountable owner behind every engagement. For more than sixteen years he has run growth for companies that do not have a marketing department of their own: strategy, execution and AI systems under one owner, from Israeli industrial exporters to eCommerce brands scaling into the US and Europe. He holds an MBA in behavioral economics and writes about answer engine optimization, performance marketing and the economics of growth.