Google Gemini 4 Carbon is now available in FastMetal chat
Gemini 4 Carbon is live in FastMetal chat. Google first released it to cyber defenders on October 28, 2026, and opened it to every developer on November 10. Google calls it its strongest model so far.
Carbon or Argon
Google is direct about this: Gemini 4 Argon remains the better choice for most software engineering and knowledge work. Carbon is for the problems that push a model to its limit, such as long multi-step coding and debugging sessions and open-ended research. A practical split is Argon for everyday work and Carbon for the tasks Argon cannot finish.
Carbon also spends more tokens than Argon. Google says it explores more, reasons longer and runs more verification loops, and those reasoning tokens bill as output tokens.
On the LMArena dataset published November 9, 2026, Carbon is first on the overall text board with a score of 1526, just ahead of Argon at 1522. That gap is inside the margin of error.
Carbon and Argon are both available on the FastMetal API and MCP server as well as in chat. Carbon's model ID is gemini-4-carbon.
What we checked before turning it on
- Image input works: it named the colors in a test image correctly.
- PDF attachments are not supported.
- The context window is 1,048,576 tokens.
- A 230,000-token prompt billed at the same per-token rate as a short one.
Pricing
Gemini 4 Carbon bills per million input and output tokens, with a separate rate for cached input. Since November 11, 2026, FastMetal's rates follow the price Google applies after its introductory period, which ends on November 30, so they will not change when that period ends. Current rates are on the Gemini 4 Carbon model page, and billing is explained on /pricing. Usage is prepaid, so you can't be charged past your balance.
How to use it
- Create a FastMetal account.
- Add credit.
- Open chat, pick Gemini 4 Carbon from the model list, and ask. You can attach images to a message.
Compare real answers first
The model page shows Gemini 4 Carbon's actual answers to FastMetal's 43 shared prompts (summarization, bug fixes, translation and more), next to Gemini 4 Argon and every other model we serve. The full catalog is at /models.