Google announced Gemini 4 Carbon on 28 October 2026 and calls it its strongest model, with state-of-the-art cybersecurity and long-horizon agent work. On Google's own launch table it leads 12 of 14 general benchmarks against GPT-6 Astra, Claude Opus 5.5, Claude Fable 5.1 and its sibling Gemini 4 Argon.
Carbon is invite-only for now, so the practical questions are which model to use today and what it costs in rupees. This post compares the models, prices them in ₹, and matches each to a real software, AI and sales job.
Google says Carbon has run for days on multi-step engineering tasks, persisting through dead ends. It also reports a 0.0% prompt-injection attack success rate, against 0.7% for Argon, and roughly half the unsupported claims of Argon in internal testing.
How the models compare
Carbon leads 12 of 14 general benchmarks. Claude Opus 5.5 still wins computer use (OSWorld-2.1), and GPT-6 Astra wins FrontierSWE 2. Carbon also leads all three cybersecurity tests. Best score per row is in bold; higher is better.
| Benchmark | Gemini 4 Carbon | Gemini 4 Argon | GPT-6 Astra | Claude Opus 5.5 | Claude Fable 5.1 |
|---|---|---|---|---|---|
| AA Intelligence Index v5.0 | 59 (best in row) | 50 | 57 | 58 | 49 |
| Vals Index v2.2 | 70.4% (best in row) | 69.2% | 65.0% | 70.2% | n/s |
| SWE-sweep (agentic coding) | 9.6% (best in row) | 4.3% | 9.5% | 3.6% | 2.9% |
| FrontierSWE 2 | 61.2% | 55.0% | 65.5% (best in row) | 62.3% | 56.3% |
| Terminal-Bench 4.0 | 65.2% (best in row) | 57.1% | 59.1% | 59.6% | 52.0% |
| Agents' Last Exam v1.1 | 77.4% (best in row) | 69.0% | 73.1% | 71.6% | n/s |
| OSWorld-2.1 (computer use) | 81.5% | 74.7% | 80.9% | 87.2% (best in row) | 76.8% |
| AutomationBench | 53.9% (best in row) | 51.3% | 41.4% | 42.5% | 31.4% |
| Vending-Bench 2 (final balance) | $16,484 (best in row) | $13,718 | $15,515 | $9,235 | $5,422 |
| Chartography | 72.5% (best in row) | 71.6% | 71.0% | 66.3% | 46.2% |
| Blueprint-Bench 2 | 58.6% (best in row) | 54.4% | 49.7% | 51.2% | 41.9% |
| GraphWalks, 256k–1M context | 96.2% (best in row) | 84.2% | 71.8% | 66.8% | 65.0% |
| RiemannBench | 80.0% (best in row) | 76.0% | 72.0% | 69.6% | 65.6% |
| Terminal-Bench-Science 0.1 | 64.8% (best in row) | 52.9% | 63.3% | 59.0% | 43.3% |
| CWE-bench (patching) | 71.0% (best in row) | n/s | n/s | 67.0% | n/s |
| ExploitGym (exploitation) | 54.8% (best in row) | n/s | n/s | 34.5% | n/s |
| SEC-bench Pro (finding bugs) | 88.2% (best in row) | n/s | n/s | n/s | n/s |
n/s = score not stated in the launch material. These are Google's own figures, as reproduced by OfficeChai; only the Artificial Analysis index is independent. Another outlet lists Argon at 53 on that index, so treat Argon's figure as uncertain.
Terminal-Bench 4.0
Higher is better, % of tasks- Gemini 4 Carbon65.2%
- Claude Opus 5.559.6%
- GPT-6 Astra59.1%
- Gemini 4 Argon57.1%
- Claude Fable 5.152.0%
GraphWalks
Higher is better, % correct- Gemini 4 Carbon96.2%
- Gemini 4 Argon84.2%
- GPT-6 Astra71.8%
- Claude Opus 5.566.8%
- Claude Fable 5.165.0%
ExploitGym
Higher is better; only Carbon and Opus 5.5 stated- Gemini 4 Carbon54.8%
- Claude Opus 5.534.5%
- Gemini 4 Argonn/s
- GPT-6 Astran/s
- Claude Fable 5.1n/s
OSWorld-2.1
Higher is better, % of tasks- Claude Opus 5.587.2%
- Gemini 4 Carbon81.5%
- GPT-6 Astra80.9%
- Claude Fable 5.176.8%
- Gemini 4 Argon74.7%
What it costs in rupees
Carbon and Argon are the cheapest at their introductory price: ₹190 per 1M input tokens and ₹951 per 1M output tokens. GPT-6 Astra and Claude Fable 5.1 cost five times that. Converted at ₹95.09 per US$ (27 October 2026).
| Model | Status | Input US$ / 1M | Output US$ / 1M | Input ₹ / 1M | Output ₹ / 1M | 1,000 documents ₹ |
|---|---|---|---|---|---|---|
| Gemini 4 Carbon | Intro price, invite-only | $2 | $10 | ₹190 | ₹951 | ₹14,264 |
| Gemini 4 Argon | Intro price | $2 | $10 | ₹190 | ₹951 | ₹14,264 |
| Claude Opus 5.5 | Standard | $4 | $20 | ₹380 | ₹1,902 | ₹28,528 |
| GPT-6 Astra | Standard, up to 272K context | $10 | $50 | ₹951 | ₹4,755 | ₹71,321 |
| Claude Fable 5.1 | Standard | $10 | $50 | ₹951 | ₹4,755 | ₹71,321 |
1,000-document job, in ₹
1,000 tender documents, each 50K tokens in and 5K out. Shorter is cheaper.- Gemini 4 Carbon₹14,264
- Gemini 4 Argon₹14,264
- Claude Opus 5.5₹28,528
- GPT-6 Astra₹71,321
- Claude Fable 5.1₹71,321
The last column is an example job of 1,000 tender documents, each 50K tokens in and 5K tokens out. Swap in your own volumes to size a real project.
Three things move these numbers. Carbon and Argon double to $4 / $20 (₹380 / ₹1,902) after the introductory period. Batch processing halves Opus 5.5 to $2 / $10 and GPT-6 Astra and Fable 5.1 to $5 / $25. GPT-6 Astra also doubles its input price above 272K tokens of context. Figures exclude GST and card forex fees.
Prices come from Google's launch post and third-party reports (Opus 5.5, GPT-6 Astra, Fable 5.1); confirm on each vendor's pricing page before budgeting. Exchange rate from Upstox.
Which model for which role and project
Use Claude Opus 5.5 for anything that drives a screen or writes code, and Gemini 4 Argon for high-volume, long-document and automation work. Move to Carbon for long documents, terminal agents and security work once it opens beyond cyber defenders.
Lead research and outreach (browser agents, UAE B2B)
- Best pick today
- Claude Opus 5.5
- Evidence from the benchmarks
- OSWorld-2.1 computer use: Opus 87.2%, Carbon 81.5%, GPT-6 Astra 80.9%
- Watch out
- ₹380 in, ₹1,902 out per 1M tokens; Carbon leads Agents' Last Exam (77.4%) for non-browser agents
Lead enquiry automation (WhatsApp, Instagram, n8n)
- Best pick today
- Gemini 4 Argon
- Evidence from the benchmarks
- AutomationBench: Argon 51.3%, Opus 42.5%, GPT-6 Astra 41.4%; Carbon 53.9%
- Watch out
- Half the price of Opus at ₹190 / ₹951, but doubles after the intro period
Tender and bid documents
- Best pick today
- Argon now, Carbon later
- Evidence from the benchmarks
- GraphWalks long context: Carbon 96.2%, Argon 84.2%, Opus 66.8%
- Watch out
- Have a person check prices, dates and eligibility clauses before submitting
Software and automation projects (code)
- Best pick today
- Claude Opus 5.5
- Evidence from the benchmarks
- FrontierSWE 2: Astra 65.5%, Opus 62.3%, Carbon 61.2%; Terminal-Bench 4.0: Carbon 65.2%, Opus 59.6%
- Watch out
- A close race; Opus costs 40% of GPT-6 Astra. Carbon for terminal-style agents when open
Security review and code auditing
- Best pick today
- Opus 5.5 now, Carbon when open
- Evidence from the benchmarks
- CWE-bench: Carbon 71.0%, Opus 67.0%; ExploitGym: Carbon 54.8%, Opus 34.5%
- Watch out
- Carbon access is limited to cyber defenders today
Client reports, charts and design documents
- Best pick today
- Gemini 4 Argon, then Carbon
- Evidence from the benchmarks
- Chartography: Carbon 72.5%, Argon 71.6%, Opus 66.3%; Vals Index: Carbon 70.4%, Opus 70.2%
- Watch out
- Differences between Carbon and Opus on general knowledge work are small
GPT-6 Astra tops only FrontierSWE 2 in this comparison and costs 2.5 times Opus 5.5. Claude Fable 5.1 does not top any row. On these numbers alone, we would not pay ₹951 / ₹4,755 per 1M tokens for either unless a test on your own data shows a clear gain.
These picks are our judgement from vendor-reported benchmarks, not tests on our own workloads. Run a small trial on real tenders, leads and code before you commit.
Want to learn to build with these models? See our live AI engineering courses or book a free orientation.
Availability, caveats and sources
Sources
- Google: Introducing Gemini 4 Carbon
- OfficeChai: Gemini 4 Carbon benchmark table
- kie.ai: Gemini 4 Carbon vs Claude Opus 5.5
- MetricNexus: Claude Opus 5.5 pricing
- eesel: GPT-6 Astra pricing
- eesel: Claude Fable 5.1 pricing
- Upstox: USD to INR rate
Frequently asked questions
What is Gemini 4 Carbon?
Gemini 4 Carbon is the model Google announced on 28 October 2026 and calls its strongest. On Google's launch table it leads 12 of 14 general benchmarks against GPT-6 Astra, Claude Opus 5.5, Claude Fable 5.1 and Gemini 4 Argon, and leads all three cybersecurity tests.
How much does Gemini 4 Carbon cost in rupees?
At its introductory price of $2 input and $10 output per 1M tokens, Carbon costs ₹190 and ₹951 at ₹95.09 per US$ (27 October 2026). The price doubles to $4 / $20 (₹380 / ₹1,902) after the introductory period, and excludes GST and card forex fees.
Is Gemini 4 Carbon cheaper than GPT-6 Astra?
Yes. GPT-6 Astra costs ₹951 input and ₹4,755 output per 1M tokens, five times Carbon's introductory price. For an example job of 1,000 documents of 50K tokens in and 5K out, Carbon costs about ₹14,264 and GPT-6 Astra about ₹71,321.
Which AI model is best for coding?
It is a close race. On FrontierSWE 2, GPT-6 Astra scores 65.5%, Claude Opus 5.5 62.3% and Carbon 61.2%; on Terminal-Bench 4.0, Carbon leads with 65.2% to Opus's 59.6%. We pick Opus 5.5 for code, at 40% of GPT-6 Astra's price.
Is Gemini 4 Carbon available to everyone?
Not yet. Access starts the week of 28 October 2026 for a subset of cyber defenders, then widens to trusted partners through the Fairwind Program, then to developers, businesses and consumers as soon as possible, with no date given.