Global AI assistant usage reached 76 billion sessions per month in September, according to an updated usage report from Graphite.
That figure marks a 37% increase from the same period a year earlier across six major AI assistants worldwide.
Unlike its March edition, the new report does not compare AI session volume directly with traditional search engines. Graphite stated that it can no longer reliably compare the size of AI used for search with search engines because the previous methodology undercounted Google search traffic originating from the Google Android app.
The session counts compiled in the report represent Similarweb estimates combining web visits and mobile app sessions. Desktop applications are omitted because reliable usage data for them does not exist, as searchenginejournal.com reported.
Mobile usage dominates total interactions with the tracked tools. In the third quarter of 2026, mobile devices accounted for 89% of global sessions and 78% of U.S. sessions.
Growth trends varied significantly across the year. Global session activity rose by 2.3% between July and December 2025 before accelerating by 19% from January through September 2026.
| Assistant | Global Growth / Share | U.S. Share |
|---|---|---|
| ChatGPT | Up 24% year over year; 58.9% of added sessions | 66% |
| Claude | Up 1,901% globally; 26% of added sessions | 11% |
| Gemini | 14% global referral share | 10% |
| Perplexity | Down 27% globally | Not specified |
Claude recorded the largest percentage increase in global session volume among all evaluated platforms. Perplexity was the sole assistant among the six to experience a decline, dropping 27% globally.
In July referral traffic distributions, ChatGPT led worldwide traffic at 60%, followed by Gemini at 14% and Claude at 10%. Domestic figures showed ChatGPT holding 66% of U.S. referral traffic, with Claude at 11% and Gemini at 10%.
Despite rising session counts, AI tools drive a minor fraction of overall web traffic. The report indicates that AI accounts for less than 1% of referral traffic to websites on average.
A separate second-quarter analysis of U.S. traffic put organic search volume at 49 times the level of AI referrals. Paid search traffic stood at eight times the volume of AI referrals during the same timeframe.
Even so, AI referral traffic expanded rapidly from its small baseline. Worldwide referral volume grew 92% year over year as of July, while U.S. referral traffic increased by 75%.
Graphite points to anecdotal evidence suggesting that some web visits generated by AI answers are misattributed to direct visits or branded search. Early internal metrics indicate that branded search traffic remains relatively flat year over year.
Similarweb data from June previously showed that 55.9% of desktop traffic arriving at a brand’s site after a ChatGPT recommendation originated through branded search.