Google has begun rolling out Gemini 4 Carbon, which it calls its most capable model yet, to AI Mode in Google Search. Access is limited to paying Google AI Ultra subscribers for now.
What is new in AI Mode
Eligible users can pick "4 Carbon" from the model menu in the "Ask anything" bar. Google's help page says the model is meant for harder queries. It describes Carbon as better at understanding intent, reasoning through difficult problems and giving more nuanced answers. The Auto and Fast options stay available for quicker, everyday questions. Robby Stein of Google said on X that the model brings deeper reasoning and better instruction following, and allows longer back-and-forth conversations in AI Mode.
Who gets access
Google said Carbon is rolling out to all Google AI Ultra subscribers in AI Mode, the Gemini app and its Antigravity development platform. According to Google's support page, users must be 18 or older and signed in to a personal Google account, and availability depends on the country. Carbon in AI Mode has daily usage limits that can change with demand and subscription plan. It is not clear when, or if, lower-tier subscribers or free users will get it.
Beyond Search
Paying developers and enterprises can use Carbon through the Gemini API in Google AI Studio and Gemini for business. It costs $2 per million input tokens and $10 per million output tokens, the same introductory price as Gemini 4 Argon. Carbon uses more tokens on hard problems, so costly tasks can come to more than the per-token rate suggests, SQ Magazine noted. Google also previewed a "swarm" feature in Antigravity that turns a single prompt into a coordinated team of AI agents.
How it got here
The wider rollout comes about two weeks after Google first gave Carbon to cyber defenders. Google describes it as a model with frontier performance in cybersecurity, long-running agentic workflows, software engineering and scientific reasoning. Argon, the earlier Gemini 4 model, reached AI Mode for Pro and Ultra subscribers on October 13. The two models now sit side by side, with Carbon positioned for the hardest tasks.
