Gemini 4 Carbon ships at $4/$20 with a Decisions API that scores 1,000 candidates per call

Carbon is the first of Google's two Gemini 4 releases this week. It is priced at $4 per million input tokens and $20 per million output tokens with a combined 1M-token context window, positioned for agentic research and coding. Perplexity CEO Aravind Srinivas moved fast, rolling it out to all Pro and Max subscribers. He claimed Carbon is "2.5x cheaper than Fable 5.2 with similar capabilities on agentic research tasks."

The more novel piece is the Gemini Decisions API. Instead of generating text, Gemini Decision 1 scores up to 1,000 candidates from a closed set in a single call. That is a native ranking and classification primitive, useful for routing, recommendation, triage and moderation, where generative output is wasteful and harder to parse. The design echoes AWS's Strands Decider. Swami Sivasubramanian highlighted on LinkedIn that an internal Amazon team replaced an LLM with Decider on a huge ticketing system at 98% lower cost. Decision models look like an emerging category.

Competitive pressure is aimed squarely at Anthropic's Fable 5.2, which Anthropic lists at $8/$40, double Carbon's price. Community side-by-sides like "Fable 5.2 vs Carbon" animation tests (223 upvotes on r/GoogleGemini) show developers actively comparing the two. Google DeepMind also amplified claims of strong coding and scientific reasoning.

The caveats: the 2.5x-cheaper claim comes from a partner with commercial incentives, and "similar capabilities" depends heavily on the task. Decisions API limits such as closed-set size and latency need real testing. Watch independent benchmarks of Carbon against Fable 5.2 and Hydrogen, and whether OpenAI or Anthropic ship their own decision endpoints.