Google Opens Gemini 4 Carbon to Developers and Businesses

Availability and pricing

Paid developers can reach Carbon through the Gemini API in Google AI Studio, and companies through Gemini for business. Google AI Ultra subscribers get it in the Gemini app, AI Mode and Antigravity, Google's agent development environment.

Carbon shares Argon's launch pricing: $2 per million input tokens and $10 per million output tokens until November 30, 2026. After that the rates are due to rise to $4 and $20. Anthropic's Claude Opus 5.5 is priced at $4 and $20, while Claude Fable 5.2 and Mythos 5.2 cost $8 and $40, so Carbon's promotional price is a quarter of Fable 5.2's. Token price is not the whole story, though: the number of tokens a model needs, retries and human intervention all shape total cost.

Agents, coding and security

Google is highlighting agent workflows. A /swarm feature, in preview in Antigravity, splits one task across several AI agents. Carbon handles architecture, coordination and oversight, while faster models work in parallel on other parts of the project.

Google says Carbon ranked first on CursorBench 4.0, Perplexity WANDR and Zapier AutomationBench, at under half the per-task cost of the next external model. On the Multimodal Knowledge Agent test built with Artificial Analysis, it placed second at an average of six times lower cost per task than the leader.

In Project Fortify, Google's internal tests, a special Carbon version offered through the Fairwind Program reached 100% recall in vulnerability scanning and 95% precision in classification. Google also says it helped uncover previously unknown flaws in some open-source software. The company expanded its researcher program to include Carbon: accepted scientists get six months of free access to Argon and Carbon on Antigravity's highest usage tier.