Gemini 4 Carbon vs Claude Opus 5.5: should you wait for Google's new model?

The short answer: Opus 5.5 now, Carbon when it opens

Choose Claude Opus 5.5 for any work you need to start this week: it is on Anthropic's API at $4 and $20 per million tokens and included in Claude Pro. Plan a trial of Gemini 4 Carbon if your work is vulnerability research or long agentic engineering, because Google reports leads on security benchmarks and an introductory price of $2 and $10, but only selected cyber defenders have access so far.

Scope and evidence

Task: choosing a frontier model for long coding agents and security review. Carbon's facts come from Google's October 28 announcement and the benchmark table on Google DeepMind's Gemini page; Opus facts come from Anthropic's Opus 5.5 overview and the Claude pricing page. All pages were read on October 30, 2026.

Every score below is a published figure from Google's table, where most rival results are as reported by their providers. AppFor.ai has not run Carbon, which is not publicly available, and did not test Opus for this page.

Compare the same criteria

Each line puts Google's claims for Carbon next to Anthropic's documentation for Opus and states the practical difference.

• Availability. Carbon: a subset of cyber defenders through the Fairwind Program, others later. Opus 5.5: Claude API and Claude apps. What this means: only Opus can be adopted now.
• API price per million tokens. Carbon: $2 input and $10 output at launch, then $4 and $20. Opus 5.5: $4 input and $20 output. What this means: Carbon would cost half during its introductory period and the same afterwards.
• Artificial Analysis Intelligence Index v5.0, per Google's table. Carbon: 59. Opus 5.5: 58. What this means: a one-point gap.
• Security tests in Google's table. Carbon: CWE-bench 71.0%, ExploitGym 54.8%. Opus 5.5: 67.0% and 34.5%. What this means: the biggest reported gap is in exploit validation.
• Coding and computer use in Google's table. Carbon: FrontierSWE 2 61.2%, OSWorld-2.1 81.5%. Opus 5.5: 62.3% and 87.2%. What this means: Opus is listed ahead on both.
• Limits. Carbon: context and output not published. Opus 5.5: 1M context, 128K output, Moderate latency, default effort medium. What this means: Opus can be planned around today.

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Which fits your real work?

A security team triaging which reported vulnerabilities are exploitable. Carbon fits on Google's ExploitGym and CWE-bench figures once the team gets access; until then Opus is the available option.

A developer running a coding agent across a large repository this month. Opus 5.5 fits because it is available and Google's own table lists it slightly ahead on FrontierSWE 2.

A Claude Pro user doing research and drafting in an app. Opus 5.5 fits, since no consumer plan includes Carbon yet.

Cost of getting the work done

API: 2 million input and 200,000 output tokens cost $12 on Opus 5.5 before caching. The same job would cost $6 on Carbon at its announced introductory price and $12 after it, with cached input 95% cheaper than standard input. Anthropic offers 50% off on its Batch API.

Apps: Claude Pro is $20 a month billed monthly and includes Opus 5.5. Google has not said which Gemini app plans will include Carbon.

Try both on the same small task

Suggested check: prepare the task now on Opus 5.5, then rerun it unchanged on Carbon when your account gets access.

• The identified flaw matches the one you planted or already know.
• The test fails before the patch and passes after it.
• The patch changes only the upload handler and its tests.
• Record tokens used so you can compare cost per task.

Decision checklist

Use the lines that match your situation. Details are in our Claude Opus 5.5 and Gemini 4 Argon profiles.

• If you need a model today, choose Opus 5.5.
• If exploit validation is your core work, apply for Carbon access and compare.
• If you price long agent runs, Carbon's introductory rate halves the token bill while it lasts.
• If computer use matters, Google's own table lists Opus ahead on OSWorld-2.1.
• If you depend on published context limits, wait for Carbon's documentation.

Go a little further

Related reading

• Claude Opus 5.5 profile →
• Gemini 4 Argon profile →
• Claude Fable 5.1 vs Claude Opus 5.5 →
• Gemini 4 Carbon profile →