How much does the Gemini 4 Carbon API cost on KeelRouter?

From $1 / $5.20 per 1M tokens. You pay per call from a prepaid USD balance; failed calls are not charged.

How do I call Gemini 4 Carbon?

Send an OpenAI-compatible request to /v1/chat/completions with model "gemini-4-carbon" and your KeelRouter API key.

Is this the official Gemini 4 Carbon API?

No. KeelRouter is an independent API gateway. Requests run on Gemini 4 Carbon through our upstream providers, and the language model keeps its own safety filters.

How long are results kept?

We keep request records (tokens and cost), not your prompts or answers.

Gemini 4 Carbon API

Language model by GoogleUp to 50% below OpenRouter1M contextReasoning

model: gemini-4-carbonPOST /v1/chat/completions

Call Gemini 4 Carbon with your KeelRouter API key, the same key you use for every other model. From $1 / $5.20 per 1M tokens, paid per call from a prepaid balance. Failed calls are free.

What is new

Released by Google on 2026-11-11. Ranked #1 on the Artificial Analysis Intelligence Index v5.0.1 (score 60 vs 59 for Claude Opus 5.5 at max effort).
Accepts text, image, audio, video and PDF input in a 1,048,576-token context window with up to 65,536 output tokens.
Priced at $1.00 / $5.20 per 1M input/output tokens on KeelRouter — 50% / 48% below Google’s $2.00 / $10.00 API list price.
Built for deep reasoning, Terminal-Bench workflows and long-document synthesis; use gemini-4-argon ($0.38 / $2.30) for routine low-latency turns.

Pricing

Option	Price
Input	$1 per 1M tokens
Output	$5.20 per 1M tokens

Token cost calculator (Gemini 4 Carbon)

Fresh input tokens (thousands)Output tokens (thousands)Cache read tokens (thousands)

Estimated call cost on KeelRouter

$0.15200000000000002

OpenRouter list ($0.30000000000000004 without cache)

Save 49% per call

Compared with OpenRouter

Options where KeelRouter costs less for Gemini 4 Carbon.

Option	KeelRouter	OpenRouter
Input	$1 per 1M tokens	$2 per 1M tokens
Output	$5.20 per 1M tokens	$10 per 1M tokens

OpenRouter list prices from its public model catalog, checked 2026-11-12; long-context surcharges not shown.

Call it

OpenAI-compatible endpoint /v1/chat/completions.

curl https://api.keelrouter.com/v1/chat/completions \
  -H "Authorization: Bearer $KEELROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gemini-4-carbon",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the sea."
    }
  ]
}'

Prompt templates

Copy-ready prompts tuned for Gemini 4 Carbon

Multi-file root-cause debugging (CursorBench pattern)

thinking: high

Best when escalating a bug that faster models failed to isolate across multiple modules.

Investigate the failing behavior described below across the provided files.

Before proposing any code edit:
1. Trace the exact data flow from entry point to failure site, citing file names and function signatures.
2. Formulate the top 2 hypotheses and prove which one is necessary and sufficient to reproduce the bug.
3. Produce a minimal, surgical patch that fixes the root cause without changing public interfaces, plus a regression test that fails before the patch and passes after.

Terminal-Bench 4.0 shell & build repair loop

thinking: high

Structured diagnostic loop for CI, Docker, and dependency resolution tasks.

You are operating in a non-interactive Linux shell environment. Your goal is to diagnose and fix the failing build/test pipeline.

Operating rules:
- Inspect logs, lockfiles, and environment versions before running mutating commands.
- Make one hypothesis-driven change at a time and verify its effect with a targeted test command.
- Never mask failures by deleting tests, weakening assertions, or adding --no-verify.

Long-context multimodal & PDF cross-document audit

1M context

Uses Carbon’s 1,048,576-token window to cross-check tables, charts, and clauses across long filings.

Cross-audit the attached documents and tables.

1. List every numerical discrepancy where a metric, date, or fee in the body text disagrees with a table, chart, or appendix.
2. For each discrepancy, quote both passages verbatim with their section/page numbers and calculate the exact delta.
3. Output a structured Markdown table ordered by financial materiality.

Parameters

Name	Type	Notes
model	string	Required. gemini-4-carbon
messages	array	Required. OpenAI chat format
max_tokens	integer	Output cap; also sets the hold
stream	boolean	Server-sent events; usage is billed at the end
temperature	number	Passed through
tools	array	Passed through when the model supports them

FAQ

How much does the Gemini 4 Carbon API cost on KeelRouter?: From $1 / $5.20 per 1M tokens. You pay per call from a prepaid USD balance; failed calls are not charged.
Is Gemini 4 Carbon cheaper on KeelRouter than on OpenRouter?: For these options, yes: Input $1 vs $2 per 1M tokens; Output $5.20 vs $10 per 1M tokens. OpenRouter list prices from its public model catalog, checked 2026-11-12; long-context surcharges not shown. No subscription; top up from $5 and pay per call.
How do I call Gemini 4 Carbon?: Send an OpenAI-compatible request to /v1/chat/completions with model "gemini-4-carbon" and your KeelRouter API key.
Is this the official Gemini 4 Carbon API?: No. KeelRouter is an independent API gateway. Requests run on Gemini 4 Carbon through our upstream providers, and the language model keeps its own safety filters.
How long are results kept?: We keep request records (tokens and cost), not your prompts or answers.

More from Google

KeelRouter is an independent service and is not affiliated with Google. Gemini 4 Carbon is a trademark of its owner, used here only to name the model a request runs on.