Graphite’s updated AI usage report puts six AI assistants at 76 billion sessions a month worldwide in September, up 37% from a year earlier. Unlike the agency’s March edition, it doesn’t compare that usage with search engines.
In March, the agency put monthly AI sessions at 56% the size of search worldwide and 34% in the U.S., with search-related AI use at 28% and 17%. The new report says that edition likely undercounted Google search use from Google’s Android app, and that the agency “can no longer reliably compare” the size of AI used for search with search engines.
The session counts are Similarweb estimates of web visits plus mobile app sessions. The report doesn’t include desktop apps because, as it explains, there isn’t reliable data available for them. Graphite sells SEO and AEO services, while Similarweb sells the data.
What Changed Since March
According to the March report, search engine usage was calculated based on website visits only (not including the apps), since the apps saw little use.
However, according to the November report, the Google Android app is different, accounting for an estimated 11.8 billion monthly sessions in the U.S. People use the app for image recognition, translation and Google Discover as well as general search. The agency says it has “no reliable data source” to determine what percent of these sessions are related to general search.
The March report’s 56% figure for total AI session usage used a web-based only count of search engines. In addition, the March report’s estimate that ChatGPT accounted for 20% of global search-related traffic used the same count. Although the new report does not revisit either of these numbers, as of this writing, the March page is still highlighting these numbers as some of the major findings from that report, though there is a link to the new report at the top.
What AI Sends To Websites
The report’s data “suggest that AI accounts for less than 1% of traffic on average” to websites. A separate chart of U.S. traffic in the second quarter of 2026 puts organic search at 49 times the volume of AI referrals and paid search at eight times.
AI referral traffic has grown from that small base, up 92% year over year worldwide as of July and 75% in the U.S. The report’s referral figures cover the top 43,000 sites among domains with at least 100,000 monthly U.S. visits in six or more months between July 2023 and July 2026. It tracks AI referrals to those sites worldwide and in the U.S.
In July, ChatGPT accounted for 60% of AI referral traffic worldwide, followed by Gemini at 14% and Claude at 10%. In the U.S., ChatGPT’s share was 66%, while Claude accounted for 11% and Gemini for 10%.
How Usage Grew
Between July and December 2025, global session activity with the six assistants increased by 2.3%. The report describes this as a plateau. Then global activity with all the assistants rose by 19% from January through September 2026.
Year-over-year growth in U.S. session activity was 45% in September.
Worldwide session activity with ChatGPT grew 24% year over year. ChatGPT also represented 58.9% of the sessions added.
Claude had the largest increase (in percent) globally, at 1,901%. Claude also generated 26% of the additional sessions. Perplexity was the only assistant among the six to show a decline, falling 27% globally.
Most global sessions occurred on mobile (mobile app or mobile web), at 89% in the third quarter of 2026. Mobile comprised 78% of sessions in the United States.
Why This Matters
Graphite’s data for Google in March was only from measuring the number of visits to Google’s website. The agency now says it can’t determine what percentage of the total usage of the Android app is search. OpenAI didn’t include the actual Google figure when it said that ChatGPT receives approximately one-fifth as many search-like queries as Google. I wrote about this on Nov. 3. The two estimates also count different things, with OpenAI logging a search whenever a question sends ChatGPT to the web and Graphite counting website visits and app sessions.
Before an AI-to-search ratio goes into a channel plan, check how its source counted Google.
Looking Ahead
Graphite cites anecdotal evidence that some visits prompted by AI answers get credited to direct visits or branded search, which AI referral reports wouldn’t catch. Its early numbers suggest branded search traffic is fairly flat year over year, with full results to come.
That measure is broader than the one in Similarweb’s June data, which I covered. Among people who visited a brand’s site after ChatGPT recommended it, 55.9% of that traffic came through branded search, in U.S. desktop data.
Featured Image: Primakov/Shutterstock
