Gemini 4 Carbon scores one point above Claude Opus 5.5 and costs 23% less per task, if you can get it
Gemini 4 Carbon scores 59 to Opus 5.5's 58 on Intelligence Index v5.0, at $7.76 a task against $10.04. Access is limited to selected cyber defenders.
GTM Architect & Growth Operator · Now · 1 November 2026 · 5 min read
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Google announced Gemini 4 Carbon on 28 October. It scores 59 on Artificial Analysis Intelligence Index v5.0, first of 58 models, one point above Claude Opus 5.5.
You probably cannot call it.
One point, on a ruler that just changed
| Info | Gemini 4 Carbon | Claude Opus 5.5 |
|---|---|---|
| Index score, v5.0 | 59 (high) | 58 (max, default fallback) |
| Rank | 1 of 58 | 2 of 58 |
| Cost per index task | $7.76 | $10.04 |
| Tokens on the run | 200M | 220M |
| List price, in / out per 1M | $4 / $20 | $4 / $20 |
| Context window | 1M | 1M |
Be careful reading anything into a point. The suite is new: Artificial Analysis moved to v5.0 in October, removed GDPval-AA and, according to VentureBeat, runs 60% of the suite on private tests or withheld answers. VentureBeat also notes that Google’s own comparison chart carries no uncertainty estimates. One point on a first run of a new suite is a tie with a ranking attached.
The effort labels do not line up either. Carbon is measured at high, Opus 5.5 at max with its default fallback. Effort settings are each lab’s own, so the rungs are not equivalent. The pair is compared at the best listed entry for each model, not at one shared setting.
Same sticker, a smaller bill
Both list at $4 input and $20 output. Carbon’s introductory $2 / $10 halves that, with cached input 95% off, and Google has not said when the introductory rate ends. For comparison, the introductory rate on Gemini 4 Argon ends on 30 November.
On the index run Carbon cost $7.76 a task and Opus 5.5 $10.04, 23% less. Carbon wrote 200 million tokens against 220 million, 9% fewer. Both are far above the 70 million median, so neither is the concise option. I cannot tell from the page why the cost gap is wider than the token gap. The likely answer is the mix of input and cached tokens, which the page does not break out.
Access is the whole story
Per VentureBeat, Google is granting access first to selected cybersecurity defenders through its Fairwind Program. The API is not generally available, and Artificial Analysis lists Carbon as lacking a public API. A Google VP said access would widen through Fairwind ahead of wider Antigravity availability and named no date.
I checked the two places a developer would look. Google’s Gemini API pricing page lists Gemini 4 Argon and has no Carbon row. The Gemini API changelog for September and October has Argon going generally available on 13 October and no Carbon entry.
Opus 5.5 sits on the other end of that spectrum. Anthropic’s models page lists it on the Claude API, Amazon Bedrock, Microsoft Foundry, Claude Platform on AWS and Claude Models on Google Cloud, at $4 / $20, with a 1M token context.
What would change my mind
An API date. A second independent run that keeps Carbon ahead. Google saying when the introductory rate ends. And a re-run at matched effort, since the labels here are not matched.
If Carbon reaches the API at $4 / $20 and holds 59 at $7.76 a task, it would be the better buy on this index, by a margin that is small on score and real on cost.
Which one I would use
Opus 5.5, today, because it is the only one of the two you can call. That is not a ruling on quality. It is a ruling on the word “available”.
When Carbon gets an API, run a hundred of your own prompts through both before you move anything. A point of index and a 23% cost gap are a reason to test. They are not a reason to switch.
The wider picture for the month is in the October digest.
Questions people asked
Is Gemini 4 Carbon better than Claude Opus 5.5?
By one point on Artificial Analysis Intelligence Index v5.0, 59 against 58, which is inside the noise of a single run. Google’s own chart carries no uncertainty estimates. Carbon is also cheaper to run on the index, $7.76 a task against $10.04.
Can I use Gemini 4 Carbon today?
Only if Google admitted you. Access began with selected cyber defenders through its Fairwind Program, and no public API date has been given. Google’s API pricing page and the Gemini API changelog list Gemini 4 Argon and no Carbon as of 1 November 2026.
How much does Gemini 4 Carbon cost?
$2 per million input tokens and $10 output at the introductory rate, $4 and $20 at the standard rate, with cached input at a 95% discount. Google has not said when the introductory rate ends. Claude Opus 5.5 lists at $4 and $20.
Which should I use, Carbon or Opus 5.5?
Opus 5.5, because it is the one you can call. Carbon’s result is worth a re-run on your own prompts once it has an API, and the cost per task suggests it will be competitive.