Gemini 4 Carbon is now open to developers, businesses and Ultra users

Carbon is on the Gemini API paid tier in Google AI Studio and in Gemini for business for all paying developers and enterprises. It is also rolling out to Google AI Ultra subscribers in Google Antigravity, the Gemini app and AI Mode in Search[1].

It launches at the same introductory price as Gemini 4 Argon, US$2 per million input tokens and US$10 per million output tokens. When that period ends on 30 November 2026, the price rises to US$4 and US$20[1].

Google is clear that Carbon is not meant to replace Argon everywhere. Argon stays the default pick for most coding and knowledge work, while Carbon spends more tokens exploring, reasoning and running verification loops on the hardest tasks[1].

Google says Carbon ranks first on CursorBench 4.0, Perplexity's WANDR and Zapier's AutomationBench at more than twice lower cost per task than the next best external model. On a new Multimodal Knowledge Agent benchmark built with Artificial Analysis, it ranks second at more than six times lower average cost per task than the leader[1].

Alongside the release, Google is previewing /swarm in Antigravity. It turns one prompt into a coordinated team of agents, with Carbon taking roles like architectural design, coordination and auditing while faster models work in parallel isolated workspaces and adversarial verifiers test each change[1]. Chosun Biz notes multiple agents can now collaborate on a task in Antigravity[2].

Because Carbon is stronger at cyber work, Google says it tightened misuse safeguards. In simulated attack environments, Carbon blocked 99% of trajectories from an adaptive red-teaming agent, and the per-attempt breach rate fell to 0.8% from 3.1% on Argon[1]. On a 375-task agentic honesty benchmark, it passed 92% of tasks compared with 70% for Argon[1]. The full cyber version, Carbon for cyber, stays behind the Fairwind Program application process.

Carbon's wider release puts a second frontier tier into Google's lineup at an introductory price well under its list rate, timed against fresh launches from Anthropic and OpenAI this week. For teams building agents, the practical question is which jobs justify Carbon's extra tokens over Argon, and /swarm is Google's answer for large, multi-agent builds.