Graphite, the SEO and AEO consultancy, estimates that six AI assistants now generate 76 billion sessions a month worldwide, up 37 percent from September 2025. The same report withdraws a comparison it published in March 2026: its authors say they can no longer reliably measure AI use against search engines. For search teams, that admission matters as much as the headline total.
The figures come from Similarweb data covering ChatGPT, Gemini, Claude, Grok, Perplexity, and DeepSeek, combined across web and app sessions. In the US the total reached 6.6 billion sessions, up 45 percent. Both rates are far below the 396 percent worldwide and 332 percent US growth in the year to September 2025. Measured over the latest quarter against the one before, the market adds 7 percent worldwide and 7.5 percent in the US.
Graphite, which sells AEO services, says Claude grew fastest in percentage terms, at 1,901 percent worldwide, ahead of Gemini at 182 percent and Grok at 123 percent. Absolute gains tell a different story. ChatGPT supplied 58.9 percent of worldwide growth in added sessions, Claude 26 percent, and Gemini 12 percent. ChatGPT still holds an 81.2 percent worldwide share, and no rival reaches 10 percent.
Perplexity moved the other way, falling 27 percent worldwide year over year. Graphite concludes that the gains for Claude and Gemini widen the AI market rather than pull users from ChatGPT, whose own sessions rose 24 percent.
Inside Google, the picture is large too. AI Mode, Google’s conversational search experience, drew 491 million US web visits in August 2026, against 360 million for the Gemini app. AI Overviews showed on 23 percent of US queries a year earlier, then on 64 percent by August 2026. Roughly two of every three US Google searches now trigger one.
Usage is mostly mobile. Graphite puts the mobile share of sessions at 89 percent worldwide and 78 percent in the US, so the US skews about twice as heavily toward desktop. The authors add that they lack a reliable source for desktop apps, so desktop use is likely undercounted.
Referral traffic is the number most SEO teams can verify in their own analytics, and it is small. Graphite’s data suggest AI supplies under 1 percent of website traffic on average. As of July 2026, ChatGPT sent 60 percent of AI referrals worldwide, with Gemini at 14 percent and Claude at 10 percent. That analysis covers the top 43,000 sites by traffic.
Graphite argues that referrals understate AI’s effect. Many AI answers offer little to click, so users may open a new tab and search for the brand, which analytics file under direct or branded search. In a case study with n8n from June 2026, AI referral visits explained only 10 percent of conversions once self-reported sources were counted. Graphite says one case study cannot support broader conclusions. It also notes that branded search traffic looks relatively flat year over year, which points against a net lift from AI visibility.
That attribution gap is why the withdrawn search comparison matters. Graphite says its March study likely undercounted Google search use through the Google Android app, which logs an estimated 11.8 billion monthly US sessions but also covers non-search tasks. It has no reliable way to separate them.
The report also shows how far company claims and third-party estimates sit apart. OpenAI cites more than 900 million weekly ChatGPT users as of March 31, 2026, while Similarweb estimates 476 million weekly active users. Graphite attributes the gap to users counted across several surfaces and devices without de-duplication. Every figure in the report is a Similarweb estimate, not a measured census.
Teams reporting on AI visibility over the next quarter should treat session totals as direction, not proof of share against search. Pair referral data with branded-search trends and self-reported attribution before telling a client AI is replacing, or failing to replace, organic traffic.
Graphite, “The State of Gen AI” by Ethan Smith and José Luis Paredes, published November 9, 2026.
