To track AI traffic in GA4, open Reports > Acquisition > Traffic acquisition and find the row called AI Assistant. Google added that default channel on May 13, 2026. It groups visits whose referrer matches Google's list of AI assistants, and Google's examples are ChatGPT, Gemini, Claude, Copilot, DeepSeek and Grok. Add Session source to see each assistant on its own row, then filter the Landing page report to see where those visitors arrived.
Treat the number as a floor. Clicks from Google's AI Overviews and AI Mode stay in Organic Search. Visits with no referrer and no tag land in Direct. And from about October 8, 2026 until a fix began rolling out on October 15, a bug stripped ChatGPT's utm_source=chatgpt.com tag, so some ChatGPT visits from that week sit in Direct too.
I read Google's Analytics help pages for this guide in October 2026. They change, so check the linked pages before you rebuild a report.
What GA4's AI Assistant channel counts
Google's default channel group page defines it in one line: "AI Assistant is the channel by which users arrive at your site from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok. It excludes Google's AI Overviews and AI Mode."
The rule underneath is narrower. A referrer is the address of the page a visitor clicked from. When "the referrer matches a list of AI Assistants," GA4 sets the session's medium to ai-assistant and its campaign to (ai-assistant), and the channel takes every session with that medium. Google doesn't publish the list. The downloadable source list on the same page covers search, social, video and shopping sites, and the copy I downloaded in October 2026 had no AI assistants in it. Neither Google page names Perplexity, so check your own source rows.
| The visit | Where GA4 puts it | Why |
|---|---|---|
| A click from an assistant on Google's list, with the referrer intact | AI Assistant | The referrer matches, so the medium becomes ai-assistant. |
| A click on a link in Google AI Overviews or AI Mode | Organic Search | Google's Organic Search definition includes them. |
| A click with no referrer and no UTM tag | Direct | Direct is source (direct) with medium (none) or (not set). |
A click tagged utm_source=chatgpt.com with no referrer | Not documented | Google's rule mentions the referrer, not tags. Check your own data. |
| A click from an AI site not on Google's list | Most likely Referral | Ordinary links get medium referral. |
ChatGPT's tag and the October 2026 gap
According to OpenAI, ChatGPT "automatically includes the UTM parameter utm_source=chatgpt.com in referral URLs." That sentence lived in a publisher FAQ OpenAI retired in October 2026, and its current search help article doesn't mention the tag.
That month the tag went missing. Search Engine Land reported that Adobe's Cedric Huesler found ChatGPT links opening in a way that suppresses referral information. On about 500 pages where ChatGPT had sent at least 5% of visits, he measured roughly 31,000 fewer ChatGPT visits a day and 26,000 more direct visits, comparing October 9 to 13 with the week before. OpenAI confirmed a known bug, and a fix began rolling out on October 15.
Huesler recommends annotating October 8 to 15 in your reports. His advice also says referral information "is still missing from most ChatGPT clicks," so the tag does most of the work of identifying ChatGPT visits. Google's channel rule talks about the referrer, so check where your chatgpt.com sessions land before you trust the AI Assistant total. Step 2 shows how.
How to track AI traffic in GA4, step by step
Step 1: Find the AI Assistant row in Traffic acquisition
- Open Reports > Acquisition > Traffic acquisition.
- Set the date range to the last 28 days.
- Find AI Assistant in the first column. Its sessions, engaged sessions and key events sit beside every other channel's.
No row? Either no AI visits matched in that range or the table uses a different channel group. Use the first column's dropdown to pick Session default channel group, Google's fixed definition. A custom primary channel group copied before May 2026 may lack the new channel. If the row stays empty for months, run the check in Step 2, then make sure AI search crawlers can reach your site.
Step 2: Split it by assistant with Session source
- Click the plus icon next to the first column header and add Session source as a secondary dimension.
- Type "AI Assistant" in the search box above the table.
- Read the sources: referring domains such as
chatgpt.com,perplexity.ai,gemini.google.com,copilot.microsoft.comorclaude.ai.
Then run the check the October gap calls for. Change the first column to Session source / medium, remove the secondary dimension and search for "chatgpt". If any row shows a medium other than ai-assistant, those ChatGPT sessions sit in another channel, and the AI Assistant total undercounts ChatGPT by that much. Repeat for "perplexity" and "gemini".
Step 3: See which landing pages AI visitors reach
- Open Reports > Engagement > Landing page.
- Click Add filter, choose Session default channel group, select AI Assistant and apply.
- Sort by sessions.
These are the pages where AI visits started, usually the page an answer linked to. A pricing or comparison page near the top suggests assistants send buyers close to a decision. An old blog post near the top tells you which question to ask the assistants yourself.
Step 4: See key events from AI visits
Key events are what GA4 used to call conversions: sign-ups, demo requests, purchases. In Traffic acquisition, the Key events column shows them by channel, and its dropdown lets you pick one event, such as generate_lead. Session key event rate shows the share of sessions with at least one.
Know which credit you're reading. Session default channel group credits the channel that started the session, using what Google calls "paid and organic channels last click." A buyer who reads a ChatGPT answer, leaves, and signs up a week later after a Google search counts toward Organic Search in this report. If AI visits on your site tend to start research rather than finish it, this view will undervalue them.
Step 5: Add a regex channel for older data or finer splits
The default channel is enough for most sites. Build your own when you need data from before May 13, 2026, because custom channel groups "can be applied to your reports retroactively." It also helps when you want one channel per assistant, or a rule that reads the source and so catches tagged chatgpt.com sessions wherever GA4 filed them.
Google's custom channel group page has an AI example, but its regex is loose. The first branch, ^.*ai, matches any source ending in "ai", including every .ai domain, and .*gpt.* matches any source containing those letters. I'd list exact domains instead:
^(.*\.)?(chatgpt\.com|perplexity\.ai|gemini\.google\.com|copilot\.microsoft\.com|claude\.ai)$This matches those five domains and their subdomains, such as www.perplexity.ai, and nothing else. The anchors make it behave the same whether GA4 treats the condition as a full or a partial match. The list is mine and needs maintaining: when a new AI site turns up in your Referral rows, add its domain. Google's page says the same, to update the regex "if URLs or the list of assistants you wish to measure change."
- Go to Admin, and under Data display, click Channel groups. You need the Editor role or higher.
- Click Create new channel group, which starts as a copy of the default group, and name it.
- Click Add new channel and name it, for example "AI assistants, regex".
- Add a condition: Source, matches regex, then paste the expression. Save the channel.
- Click Reorder and drag the channel above Organic Search, AI Assistant and Referral, but below the paid channels so tagged ad clicks stay paid. GA4 puts each session in the first channel it matches. Apply, then save the group.
- In Traffic acquisition, switch the first column to your new group.
For one channel per assistant, add five channels, each with its own condition:
| Channel | Source matches regex |
|---|---|
| ChatGPT | ^(.*\.)?chatgpt\.com$ |
| Perplexity | ^(.*\.)?perplexity\.ai$ |
| Gemini | ^(.*\.)?gemini\.google\.com$ |
| Copilot | ^(.*\.)?copilot\.microsoft\.com$ |
| Claude | ^(.*\.)?claude\.ai$ |
A standard property gets two custom channel groups and a 360 property five, each with up to 50 channels. Edits apply to past data at once, so old exports may disagree with new reports.
To avoid spending a slot, use an exploration. In Explore, start a Free form exploration with Session source and Landing page + query string as rows, Sessions and Key events as values, and a filter on Session source that matches regex, using the same expression. It changes nothing in the standard reports.
What GA4 can't tell you about AI search
Mentions that never become clicks
An answer can name you, recommend you or cite your pricing page, and the buyer can act on it without clicking. On Google, Pew measured clicks on a link inside the AI summary on 1% of visits to search pages that showed one. If that buyer later types your URL or searches your brand, GA4 files the visit under Direct or Organic Search, and the assistant gets no credit.
AI Overviews and AI Mode versus regular results
Both sit in Organic Search with ordinary result clicks, and GA4 can't separate them. Search Console's generative AI performance report, live for all sites since August 31, 2026, counts impressions of your links in AI Overviews and AI Mode by page, country, device and date. Its help page mentions no click metric, so it shows where you appeared, not who came. I cover it in how to track AI Overviews and AI Mode.
Which question sent the visit
A referrer tells GA4 which site a visitor came from, not what they asked. You can see a visit from perplexity.ai to your pricing page. You can't see whether the answer recommended you, listed you among four rivals or warned against you.
Where to get what GA4 misses
| Source | What it shows | What it doesn't |
|---|---|---|
| GA4 AI Assistant channel | Sessions, landing pages and key events from AI referrers | Answers without clicks, AI Overviews and AI Mode, the question asked |
| Search Console generative AI performance report | Impressions of your links in AI Overviews and AI Mode | Clicks, going by its help page, and assistants outside Google Search |
| Bing Webmaster Tools AI Performance | Citations of your pages in Microsoft Copilot, AI summaries in Bing and "select partner integrations" | Clicks, and which partners count. Microsoft doesn't say whether ChatGPT is one. |
| Answer tracking, by hand or with a tool | Whether each answer names you, recommends you or cites your page, and who appears instead | Traffic. Each run is one sample, so it needs repeats. |
Microsoft launched AI Performance in Bing Webmaster Tools as a public preview on February 10, 2026, with citations by URL and a sample of grounding queries.
Answer tracking is the only one of the four that separates named, recommended and cited. Ask the assistants your buyers' questions several times each and record what comes back, because answers move: Envoyra, which sells AI visibility tracking, found 79% of question and assistant pairs changed their brand list at least once over four weekly runs. The manual method is in how to get cited by ChatGPT.
How to read AI traffic numbers in GA4
Read small numbers as small
Small counts swing by chance. A page that went from 6 AI sessions to 11 may not have changed at all; one person sharing a link could do that. My rule of thumb, not a statistic: I don't read much into a page until it has a few dozen AI sessions per period and moves the same way two or three periods running.
Mark October 8 to 15, 2026
Any comparison that touches that week shows ChatGPT falling and Direct rising on the same pages. Until about December 10, 2026, either the last 28 days or the 28 before will include part of it. Look at ChatGPT and Direct together on pages ChatGPT used to send visitors to. If Direct rose by roughly what ChatGPT lost, that's the bug, not your buyers.
Compare 28 days with the previous 28, by landing page
Open the Landing page report with the AI Assistant filter from Step 3. In the date picker, choose Last 28 days, turn on Compare and pick the preceding period. Twenty-eight days is four whole weeks, so both periods have the same weekdays. Here is the result as an invented example; the pages and numbers are placeholders, not real data.
| Landing page | AI sessions, last 28 days | AI sessions, previous 28 | Key events, last 28 days |
|---|---|---|---|
| /pricing | 41 | 18 | 6 |
| /compare/your-brand-vs-competitor | 22 | 9 | 2 |
| /blog/late-invoice-reminders | 15 | 21 | 0 |
| / | 12 | 11 | 1 |
Here the pricing page more than doubled and produced most key events, the blog post slipped and the home page held. What I'd write in a report: "AI Assistant sessions to /pricing rose from 18 to 41 in the 28 days after we added a plan comparison table, and answer tracking showed ChatGPT citing that page in more runs." What I wouldn't write: "The table brought 23 extra AI visits."
Report association, not cause
Too much changes at once to pin a rise on one piece of work. Answers shift weekly, models get updated, tags break, competitors publish and buyers have seasons. A rise after your new page went live is consistent with the page helping. It doesn't prove it. Write "rose after", never "because of", and put answer tracking beside it.
Frequently asked questions
Can Google Analytics 4 track ChatGPT traffic?
Yes, partly. Since May 13, 2026, GA4 puts visits from ChatGPT and other AI assistants with a matching referrer in a default channel called AI Assistant, and according to OpenAI, ChatGPT tags its links with utm_source=chatgpt.com. Visits with neither land in Direct, so treat the count as a minimum.
Why does ChatGPT traffic show up as direct in GA4?
When a visit has no referrer and no UTM tag, GA4 can't tell where it came from and files it under Direct. That happened to many ChatGPT visits from October 8 to 15, 2026, when a bug removed ChatGPT's tag. It also happens when someone copies a link out of an answer or comes back later by typing your URL.
Does GA4's AI Assistant channel include Google AI Overviews and AI Mode?
No. Google's definition excludes them from AI Assistant and includes them in Organic Search, mixed with ordinary search clicks. Search Console's generative AI performance report shows their impressions by page, but no clicks.
Is Perplexity traffic counted in the AI Assistant channel?
Google hasn't published its list, and neither of its pages on the channel names Perplexity. Add Session source to Traffic acquisition and see which channel your perplexity.ai sessions sit in. If they're in Referral, the regex channel above groups them with the rest. For getting cited there in the first place, see Perplexity SEO.
How do I see AI traffic from before May 2026?
The AI Assistant channel started on May 13, 2026, and Google doesn't say whether it reclassified earlier visits. Custom channel groups apply retroactively, so a group with a regex on source shows earlier AI visits too.
What is utm_source=chatgpt.com?
It's a tag OpenAI said ChatGPT adds to the links it sends, so analytics tools can attribute the visit. GA4 reads it as the session source chatgpt.com. OpenAI documented it in a publisher FAQ it retired in October 2026, and a bug removed the tag for about a week that month.
Check your AI Assistant row this week
Open Traffic acquisition, find AI Assistant and add Session source. Search for "chatgpt" to see where those sessions really land. Filter the Landing page report to AI Assistant and write down the top five pages with sessions and key events for the last 28 days and the 28 before. Mark October 8 to 15, 2026. That's your baseline.
Then look at the half GA4 can't see: the answers. The free AI visibility report checks 5 of your buyer questions across ChatGPT, Gemini, Perplexity, Google AI Overviews and AI Mode, and shows whether each answer names you, recommends you or cites your pages, and who shows up instead. No card needed.