How much does the Gemini 4 Carbon API cost?

On FastMetal, Gemini 4 Carbon is billed per token: $4.22 per 1M input tokens and $21.10 per 1M output tokens on a US-dollar account, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.

Can I call Gemini 4 Carbon with the OpenAI SDK?

Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "gemini-4-carbon" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.

What is the context window of Gemini 4 Carbon?

1,048,576 tokens, shared between the prompt and the response.

What do I need to try Gemini 4 Carbon?

Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.

Back to Models

Google

gemini-4-carbon

Gemini 4 Carbon

Gemini 4 Carbon is a frontier Gemini 4 model from Google for coding, agentic and complex reasoning work. It takes text, image, audio, video and file input, supports long decode...

11/10/2026

1,048,576 tokens

Input: $4.22/M

Output: $21.10/M

Try in Chat Get API Key

Specifications

Modalities

Input

audio

file

image

text

video

Output

text

Supported Parameters

include_reasoning

max_tokens

reasoning

reasoning_effort

response_format

seed

stop

structured_outputs

temperature

tool_choice

tools

top_p

Max Output Tokens

943,718

Reasoning Configuration

Default: Thinking on (effort: medium)
Selectable effort levels: high
medium
low
Turning thinking off: Not possible (always thinks)

How to control thinking, and what it costs

Data policy

Prompt retention: Unknown: we could not confirm
Training: Unknown: not declared

"Unknown" does not mean "safe". It means we could not confirm it.

Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.

Code Examples

curl https://api.fastmetal.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gemini-4-carbon",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

How Gemini 4 Carbon actually answers

Real responses to our standard prompts, recorded on FastMetal.

Count the number of 'r's in 'strawberry'

Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.

There are **3** 'r's in the word "strawberry". Here is the step-by-step breakdown: 1. **Write out the word letter by letter:** s - t - r - a - w - b - e - r - r - y 2. **Check each letter one by one and count the 'r's:** * **s** (not an 'r') * **t** (not an 'r') * **r** — **1st 'r'** * **a** (not an 'r') * **w** (not an 'r') * **b** (not an 'r') * **e** (not an 'r') * **r** — **2nd 'r'** * **r** — **3rd 'r'** * **y** (not an 'r') 3. **Add them up:** There is one 'r' in "st**r**aw" and two 'r's in "be**rr**y". 1 + 2 = **3**.

12.6s response503 output tokens

Debug This Error

I'm getting the following error in my Node.js application: TypeError: Cannot read properties of undefined (reading 'map') at UserList (/app/components/UserList.js:12:25) at renderWithHooks (/app/node_modules/rea…

### What is causing this error? This error means that the `users` prop being passed into your `UserList` component is `undefined` at the time the component tries to render. Since `undefined` is not an array, JavaScript crashes when it tries to call `.map()` on it. In React, this most commonly happens for one of two reasons: 1. **Asynchronous data fetching:** You are fetching `users` from an API in a parent component. On the very first render (before the API responds), the data hasn't arrived yet, so `users` is `undefined`. 2. **Missing prop:** You rendered `<UserList />` somewhere in your app and forgot to pass the `users` prop entirely. --- ### How to fix it Here are the three best way…

27.3s response952 output tokens

Code Review

Please review the following Python function and suggest improvements for readability, performance, and best practices: def get_data(url, retries=3): import requests import time for i in range(retries):…

Here is a comprehensive review of your function, categorized by best practices, readability, and performance, followed by two refactored versions. ### Key Areas for Improvement #### 1. Best Practices & Bug Risks * **Bare `except:` clause:** Using `except:` catches *everything*, including `KeyboardInterrupt` (Ctrl+C) and `SystemExit`, making it hard to stop your program. It also hides bugs in your own code (e.g., if `r.json()` returns a dictionary instead of a list, or if `"name"` is missing, it will silently fail and retry instead of alerting you to the data structure issue). Catch `requests.RequestException` instead. * **Imports inside the function:** Per PEP 8, imports should be at the t…

26.7s response1593 output tokens

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Frequently asked questions

How much does the Gemini 4 Carbon API cost?: On FastMetal, Gemini 4 Carbon is billed per token: $4.22 per 1M input tokens and $21.10 per 1M output tokens on a US-dollar account, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.
Can I call Gemini 4 Carbon with the OpenAI SDK?: Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "gemini-4-carbon" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.
What is the context window of Gemini 4 Carbon?: 1,048,576 tokens, shared between the prompt and the response.
What do I need to try Gemini 4 Carbon?: Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.