45 billion monthly sessions. That is how much traffic AI assistants now generate worldwide, according to a new analysis from Graphite.io CEO Ethan Smith. The report, titled "AI Is Much Bigger Than You Think," combines web traffic and mobile app data to put a number on something many of us have felt intuitively: AI tools are handling a massive share of the questions people used to type into Google.
The headline figure is striking. AI platforms now account for activity equal to 56% of global search engine volume. In the U.S. specifically, the number is 34%, or about 5.4 billion monthly sessions.
ChatGPT Dominates, Everyone Else Fights for Scraps
The analysis tracked five major AI products: ChatGPT, Google Gemini, Perplexity, Grok, and Claude. ChatGPT alone accounts for 89% of global AI sessions, a concentration that makes Google's old search dominance look competitive by comparison.
But there is a crucial nuance buried in the data. When you filter down to just search-like prompts (questions where someone would have previously used a search engine), AI usage drops to 28% of search volume globally and 17% in the U.S. The rest of that 56% figure includes tasks like writing, coding, image generation, and analysis that never would have been search queries in the first place. AI is not just replacing search - it is creating entirely new categories of usage.
Google's Shrinking Slice
Google's share of search-related activity fell from 89% in 2023 to 71% by Q4 2025. That is an 18-percentage-point drop in two years, a pace of decline that would have seemed impossible before ChatGPT launched.
The total pie is growing, though. Combined usage across search engines and AI assistants grew 26% globally since 2023. So Google is losing share of a larger market, not necessarily losing raw volume - at least not yet.
Mobile Is Where It Is Happening
83% of global AI usage happens through mobile apps, not web browsers. In the U.S., that number is 75%. This matters for anyone thinking about SEO and content strategy, because mobile AI app users are not clicking through to websites the way desktop search users do. The traffic pattern is fundamentally different.
U.S. AI usage grew roughly 300% year over year by December 2025, though global growth has plateaued since July 2025. That plateau suggests the early-adopter wave may have crested internationally, while the U.S. market still has room to grow.
What This Means for Your Traffic Strategy
The practical takeaway from this data is not that search is dying. It is that the discovery landscape has split. People still use Google, but a growing chunk of information-seeking behavior now happens inside ChatGPT and similar tools, where your website either shows up in AI-generated answers or it does not.
Smith's conclusion - that businesses now need both traditional search rankings and visibility within AI models - sounds obvious, but most companies have done exactly zero work on the AI side. If you are still treating SEO as your only discovery channel, this report is a concrete reminder that the ground has shifted under you.