GA4 shows chatgpt.com traffic but not which pages or prompts: how we prove AI search ROI

The setup is almost always the same. A client opens GA4, finds chatgpt.com in the sources, and asks us two questions. Which pages is it landing on, and what were people asking? The first is answerable. The second is not, at least not directly, and we say so on day one. Then we build the best honest answer we can from the data that does exist.

Start with what the click contains

A visit from ChatGPT carries a referrer of chatgpt.com. Browsers send the origin only for cross-site requests like this, so the conversation is not included. There is no prompt in the click, in GA4 or anywhere else in your analytics. ChatGPT search links also carry utm_source=chatgpt.com, per OpenAI's publisher guidance, without a utm_medium, which in GA4's default grouping can push visits into Unassigned or leave the medium as (not set). Visits from some apps arrive with no referrer at all and land in Direct. So the GA4 number is a floor.

We do three things inside GA4 first. We create a custom channel group matching AI referrers by source and move it above Referral. We add Landing page as a secondary dimension to see where the traffic goes. And we verify that redirects keep query strings, because broken redirects quietly strip the UTM.

Recover the pages, infer the prompts

The page is knowable. The prompt is inferable. Here is the logic we use with clients. We track a set of prompts across engines and record which pages get cited for each. Then we look at AI-referred visits per page. If a page is cited for several commercial prompts and receives most of the AI traffic, those prompts are the likely drivers. It is an inference, we label it that way, and it still gives the client a clear list of pages and prompts worth protecting.

What we run it on

Our client programs run on Promptwatch, because the join we just described is built in. Visitor analytics attributes AI-referred traffic and conversions across ChatGPT, Perplexity, Gemini, Claude, Copilot, DeepSeek, Kimi and Mistral, installed through a lightweight script, a GTM template or the WordPress plugin. Citation analytics shows which pages are cited for tracked prompts. 360 Insights joins crawler logs, citation clicks and AI-referred visits per page, so one row says whether a page was crawled, cited and visited. Agent Analytics shows IP-verified AI crawler visits, which answers the "is the bot even reaching it" question. Search Insights adds Google Search Console and Bing Webmaster data.

For reporting, dashboards and PDF reports, including scheduled ones, give the client something to forward. Agent Chat can build charts from live data when a stakeholder asks a follow-up in a meeting.

Evidence from customers, attributed properly

Promptwatch publishes two case studies we point clients to, with the caveat that they are those customers' results. Crisp reported that AI-referred traffic converted at twice the rate of traditional channels. TreeHouse (Pararius and Huurwoningen.nl) reported that AI search became about a quarter of its organic conversions, nearly all from ChatGPT, after it fixed crawler access and automated weekly reporting. We cite these as examples of what the measurement can show, never as a forecast for a client.

How we build the ROI case

Pick the conversion. One primary event: demo, signup, purchase.
Instrument twice. GA4 with the custom channel, plus the AI analytics script, then compare.
Benchmark against the client's own organic. We never borrow an industry average.
Report a floor. The number is a minimum, and we explain why.
Track by page. Cited pages, their AI visits and conversions, month over month.
Tie in visibility. Share of voice for the prompts behind those pages.
Review monthly. AI traffic grows unevenly, and a single month can mislead.

Plan notes

Essential ($95 a month) includes 200K visitor events and no crawler logs. Professional ($245) includes 1M visitor events, 25M crawler logs and custom reports. Business ($579) includes 10M visitor events and 100M crawler logs. The agency self-serve plans, Kick-off ($199), Growth ($399) and Scale ($799), include visitor analytics and crawler logs. A free Explore plan covers tracking basics with 10 prompts on ChatGPT.

The sentence we put in front of finance

"AI search sent this many measured visits and this many conversions, which is a floor. The pages involved are these, and the prompts that cite them are these. Here is the trend." That holds up in a budget review. A claim that prompt X produced sale Y does not, and nobody should make it.