Short answer: Gemini 4 Carbon is the Google DeepMind model announced on October 28, 2026, which Google calls its “strongest model,” built for long-running agentic and cybersecurity work. As of November 1, 2026 it is a limited release for a subset of cyber defenders and trusted partners. It is not in the Gemini app, AI Mode, AI Overviews or the public API. The Gemini 4 model you can use in Google Search today is Gemini 4 Argon, which reached AI Mode for Pro and Ultra subscribers on October 13. Some videos and posts call it “Gemini 4.0 Cobalt,” but Google’s name for the model is Carbon.
By Garry Grant, CEO of SEO Inc. Updated November 1, 2026. Every fact below links to its source.
What is Gemini 4 Carbon?
Google DeepMind introduced Gemini 4 Carbon on October 28, 2026 in a post by Koray Kavukcuoglu, SVP of Google DeepMind and Google’s Chief AI Architect, titled “Gemini 4 Carbon: our next frontier model.”
Google positions Carbon for sustained agentic work: tasks that run for hours or days, such as finding the root cause of a bug across a large codebase and patching it. It builds on Gemini 4 Argon, released October 13, and uses the same safety stack. Google reports these results from its own internal testing:
Secure code
More than twice Argon’s success rate at generating secure code.
Fewer unsupported claims
About half as many unsupported claims as Argon.
Alignment
Nearly 80% fewer high-severity misalignment alerts in internal coding environments.
The Gemini 4 family has two models so far, Argon and Carbon. Google has not published a Pro/Flash tier structure for Gemini 4, and Gemini 3.x models, including Gemini 3.8 Flash, are still listed in the developer docs.
Is it Gemini 4 Carbon or Gemini 4.0 Cobalt?
The official name is Gemini 4 Carbon. Google’s launch post, the Gemini developer docs and independent benchmark sites all use “Carbon.” We found no Google or DeepMind source for a model called “Cobalt.” If you have seen “Gemini 4.0 Cobalt” in a video title or a social post, it refers to Carbon, the model Google announced on October 28, 2026.
Many YouTube creators covered the launch within days, including Paul J Lipsky, WorldofAI and Bruno Vega. The videos are useful for seeing the model at work, but treat claims in a video title (for example, that Carbon “clearly beat” every rival) as opinion until a benchmark backs them. The independent scores below give the fuller picture.
Gemini 4 Carbon benchmarks: Google and independent scores
| Benchmark | Gemini 4 Carbon | Source |
|---|---|---|
| Artificial Analysis Intelligence Index v5.0 | 59, ranked #1 (Argon about 50) | Artificial Analysis |
| Coding Agent Index | 59 (Claude Code with Opus 5.5: 62) | Artificial Analysis |
| Hallucination rate | 11% (Argon: 4%) | Artificial Analysis |
| Vals Index | 70.36%, ranked #2 | Vals AI |
| Vals Finance Index | 66.35%, ranked #1 | Vals AI |
| Legal Research Bench | 55.77%, ranked #1 | Vals AI |
| SEC-bench Pro (finding vulnerabilities) | 88.2% | |
| CWE-bench (patching) | 71.0% | |
| ExploitGym | 54.8% | |
| Gray Swan prompt-injection attack success | 0.0% (Argon: 0.7%) |
Two caveats. Google says its cyber benchmarks were run without guardrails, and the ExploitGym score used a 10-hour time limit; one independent review reports 53.5% at 6 hours. Carbon leads most general indexes but not every one: Artificial Analysis still ranks Claude Code with Opus 5.5 ahead of it on coding agents.
Who can use Gemini 4 Carbon, and what does it cost?
As of November 1, 2026, Carbon is a limited release. Google says it is available to “a subset of cyber defenders,” with access widening gradually to trusted partners through Google DeepMind’s Fairwind Program. Governments, critical infrastructure operators and core technology platforms get priority, and organizations apply through their Google Cloud account team. Google has not given a date for wider access, saying only that developers, businesses and consumers will get it “as soon as possible.”
| Gemini 4 Argon | Gemini 4 Carbon | |
|---|---|---|
| Released | October 13, 2026 | October 28, 2026 |
| Gemini app | Yes, AI Pro and Ultra | No |
| Google AI Mode | Yes, Pro and Ultra (model menu) | No |
| Gemini API / AI Studio | Yes | No (Fairwind partners only) |
| Price per 1M tokens | $2 in / $10 out introductory, then $4 / $20 | $2 in / $10 out introductory, then $4 / $20 |
| Context window | 1M tokens (Google) | 1M tokens (third-party listings; Google has not stated it) |
Google’s introductory pricing for Argon ends November 30, 2026. Cached input is discounted 95%. One benchmark site describes $4 / $20 as the discounted rate, but we use Google’s published figures.
Does Gemini 4 Carbon change Google Search?
Not yet. Google’s Carbon announcement does not mention Search, AI Overviews or ads.
The Gemini 4 change that already affects Search is Argon. On October 13, Google added Argon to the AI Mode model menu (the “+” icon) for Google AI Pro and Ultra subscribers, and Robby Stein, VP of Product for Search, said it is rolling out globally. Search Engine Roundtable reports that Argon’s AI Mode answers include links to sources. Free users still get the default model; Google made Gemini 3.5 Flash the global default at I/O in May, and has announced no change since.
That means two groups of people can now see different AI answers to the same question: paid subscribers on Argon and free users on the default model. Google has announced no changes to AI Overviews or Google Ads tied to either Gemini 4 model.
What businesses and marketers should do now
Don’t overpromise
Carbon is not changing AI Overviews or AI Mode today. Tell stakeholders the live change is Argon in paid AI Mode.
Make pages easy to cite
Argon’s AI Mode answers include links. Clear answers, one fact per sentence and visible sources make a page easier to quote.
Lead with verifiable facts
Google’s launch post leans on fewer unsupported claims. First-party data, named authors and linked sources give a model something to trust.
Track paid and free answers
Check AI visibility on both the default model and Argon, since the two audiences can see different answers.
Budget for API prices
If you build tools on Gemini 4, the introductory $2 / $10 pricing is scheduled to rise to $4 / $20.
Patch your site
Carbon’s cyber focus is a reminder that AI finds vulnerabilities faster. Keep your CMS, plugins and themes updated.
SEO Inc. helps businesses earn citations in Google AI Mode, AI Overviews, ChatGPT and Gemini. See our professional SEO services, our guide to the latest AI search changes, and our PPC management for paid search in AI results.
Gemini 4 Carbon FAQ
What is Gemini 4 Carbon?
Gemini 4 Carbon is a Google DeepMind AI model announced on October 28, 2026. Google calls it its strongest model, with state-of-the-art cybersecurity and long-horizon agentic capabilities. It builds on Gemini 4 Argon, released October 13, 2026.
Is it called Gemini 4 Carbon or Gemini 4.0 Cobalt?
Google’s official name is Gemini 4 Carbon. There is no Google model called Gemini 4 Cobalt; the name appears in some videos and posts but refers to Carbon.
When was Gemini 4 Carbon released?
Google announced Gemini 4 Carbon on October 28, 2026 as a limited release. Broader access for developers, businesses and consumers has no published date.
Can I use Gemini 4 Carbon?
Not yet, for most people. As of November 1, 2026, Carbon is available to a subset of cyber defenders and is widening to trusted partners through Google DeepMind’s Fairwind Program, applied for through a Google Cloud account team. It is not in the Gemini app, AI Studio or the public Gemini API.
Does Gemini 4 Carbon power Google AI Mode or AI Overviews?
No. Google’s announcement does not mention Search. The Gemini 4 model in AI Mode is Gemini 4 Argon, available to Google AI Pro and Ultra subscribers through the model menu since October 13, 2026.
How much does Gemini 4 Carbon cost?
Google lists an introductory price of $2 per million input tokens and $10 per million output tokens, rising to $4 and $20, with cached input discounted 95%. Access is currently limited to Fairwind partners.
How does Gemini 4 Carbon rank on benchmarks?
Artificial Analysis ranks it #1 on its Intelligence Index v5.0 with a score of 59. Vals AI ranks it #2 on the Vals Index and #1 on its Finance Index and Legal Research Bench. Claude Code with Opus 5.5 still scores higher on the Artificial Analysis Coding Agent Index.
What does Gemini 4 Carbon mean for SEO?
Nothing changes in Search today because Carbon is not in AI Mode or AI Overviews. The practical steps are to make pages easy for AI to cite, lead with verifiable facts and sources, and track AI visibility for both free and paid AI Mode users.
Sources
- Google: Gemini 4 Carbon, our next frontier model (Oct 28, 2026)
- Google: Gemini 4 Argon, built to solve your hardest problems (Oct 13, 2026)
- Google DeepMind: Fairwind Program
- Google AI for Developers: Gemini models
- Artificial Analysis: Gemini 4 Carbon is the new #1 (Oct 28, 2026)
- Vals AI: Gemini 4 Carbon model page
- Reuters via Khaleej Times: Google launches Gemini 4 Carbon (Oct 28, 2026)
- Search Engine Roundtable: Gemini 4 Argon in Google Search via AI Mode (Oct 13, 2026)
- Search Engine Journal: Gemini 4 Argon in AI Mode (Oct 13, 2026)
- Jake Handy: Model Drop, Gemini 4 Carbon
- YouTube, Paul J Lipsky: Google Just Announced Gemini 4 Carbon
- YouTube, Bruno Vega: Gemini 4 Carbon explained
Facts checked November 1, 2026. Figures belong to the cited publishers; where Google or OpenAI has not published a number, we say so.
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