Claude Opus 5.5 vs Gemini 4 Argon: API price, context and cost per task
The two newest flagships: Claude Opus 5.5 (22 September 2026) and Gemini 4 Argon (30 September 2026). Both target long, multi-step work, but Argon is still rolling out and its launch price is an introductory rate.
On output, Gemini 4 Argon is 2x cheaper ($10 vs $20 per million tokens). On input, Gemini 4 Argon is 2x cheaper ($2 vs $4 per million tokens). Gemini 4 Argon reads more per request: 1,048,576 tokens against 1,000,000.
Data updated 2026-11-11 - source: public OpenRouter model list, refreshed daily. Prices in USD, excluding VAT.
Specs and prices side by side
| Claude Opus 5.5 | Gemini 4 Argon | |
|---|---|---|
| Vendor | Anthropic | |
| Input, per 1M tokens | $4 | $2 |
| Output, per 1M tokens | $20 | $10 |
| Cached input, per 1M | $0.2 | $0.1 |
| Batch (input / output) | $2 / $10 | $1 / $5 |
| Context window | 1,000,000 | 1,048,576 |
| Max output | 128,000 | 943,718 |
| Input types | text, images, files | text, images, files, audio, video |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| On OpenRouter since | 22 Sep 2026 | 13 Oct 2026 |
Highlighted: the cheaper price or the larger limit. "Not published" means the figure is not in the public model listing yet.
What a month of work costs
Four typical workloads at today's list prices. Reasoning models also bill their thinking as output tokens, so treat output-heavy numbers as a floor.
| Workload | Claude Opus 5.5 | Gemini 4 Argon | Difference |
|---|---|---|---|
| Support chatbot10,000 conversations a month, about 1,500 input and 400 output tokens each | $140 | $70 | Gemini 4 Argon 2x cheaper |
| Coding agent300 tasks a month, about 80,000 input tokens (code context re-read across steps) and 8,000 output tokens each | $144 | $72 | Gemini 4 Argon 2x cheaper |
| Coding agent with caching70% of input served from the prompt cache | $80.16 | $40.08 | |
| Long-document analysis1,000 documents a month, about 50,000 tokens in and a 1,500-token summary out | $230 | $115 | Gemini 4 Argon 2x cheaper |
| Content drafting600 articles a month, about 3,000 tokens of brief in and 2,500 tokens of draft out | $37.20 | $18.60 | Gemini 4 Argon 2x cheaper |
Price stability over the last 30 days
- Claude Opus 5.5: no change in the last 30 days.
- Gemini 4 Argon: no change in the last 30 days.
What the vendors and benchmarks say
Claude Opus 5.5
"Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5."model card on OpenRouter
- Released on 22 September 2026 as the first model of the Claude 5.5 family. Source: Anthropic
- Anthropic says a typical task at default settings costs 40% less than on Opus 5, because the model uses fewer tokens, and that generation is over 30% faster. Source: Anthropic
- Thinking is always on and cannot be switched off; the default effort level is medium (Opus 5 defaulted to high). Source: Anthropic model documentation
- Terminal-Bench 4.0: 66.4%; GDPval-AA v2.1: 1846 Elo. In Anthropic's test, 16 of 18 reports written from incomplete sources contained no invented figure. Source: Anthropic
- Fast mode costs $8 / $40 and batch mode $2 / $10 per million tokens; knowledge cutoff June 2026. Source: Anthropic
Gemini 4 Argon
"Gemini 4 Argon is Google's flagship reasoning model, built for complex software engineering, deep mathematical and scientific problem solving, and autonomous multi-step agents."model card on OpenRouter
- Announced on 30 September 2026 - Google's first new flagship generation since Gemini 3 in November 2025. Source: Google
- The output limit grew from 64,000 to 1,000,000 tokens, which Google calls the highest in the industry. Source: Google
- Introductory API rate: $2 input / $10 output per million tokens, cached input 95% cheaper. After the introductory period: $4 / $20. Source: Google
- Google-reported results: DeepSWE v1.1 77.9%, AutomationBench 51.3% (1st), LVBench 91.7%. Text Arena 1525 (1st), but Code Arena WebDev 1679 (8th). Source: Google; arena rankings
- Staged access: trusted testers first, then paying API customers and Google AI Ultra subscribers. Not in the public API as of 30 September 2026. Source: Google
Which one to pick
Argon's introductory rate undercuts Opus 5.5, but Google has said it rises to $4 / $20 after the intro period - the same list price Opus 5.5 launched with. Argon's headline features are the 1,000,000-token output limit and strong agent, legal and finance results reported by Google; its 8th place in Code Arena WebDev suggests mixed coding results. Opus 5.5 is generally available today, which for production work decides it until Argon reaches the public API.
Cheaper models with a similar context window
Models from our comparison set that cost less than both on a blended basis and support tool calling. They are not equivalent in quality - test before switching.
- Qwen3.8 Max (Alibaba (Qwen)): $2 / $6 per million tokens, 1M context
- Gemini 3.8 Flash (Google): $0.825 / $4.13 per million tokens, 1.05M context
- DeepSeek V4 Pro (DeepSeek): $0.955 / $1.91 per million tokens, 1.05M context
Related reading
- Gemini 4 Argon Test: 23 Tasks vs Opus 5.5 and GPT-6 Astra
- Gemini 4 Argon vs GPT-6 Astra vs Claude Opus 5.5 Benchmarks
- Claude Fable 5.2 vs Opus 5.5: Price, Benchmarks, Which to Pick
- Claude Opus 5.5 vs GPT-6 Astra: Plan or API?
- Claude Pro vs. Max vs. API: Opus 5.5 costs compared
- Gemini 4 Carbon test: 50+ tasks vs Argon, Claude Fable 5.2 and GPT-6.1 Sol
How we calculate
Prices are the public per-token list rates from OpenRouter's model list, which match the vendors' own API prices for first-party models and show the current routed price for open-weight models served by several hosts. Monthly costs multiply those rates by the token volumes in each workload; caching assumes the stated share of input is billed at the cached-input rate. Benchmarks and claims are quoted from the named sources, mostly the vendors themselves - treat them as a guide and test on your own tasks. See also the AI cost calculator and all tracked model prices.
Frequently asked questions
Which is cheaper, Claude Opus 5.5 or Gemini 4 Argon?
As of 11 Nov 2026, Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens; Gemini 4 Argon costs $2 and $10. Claude Opus 5.5 is cheaper in 0 of the 4 monthly workloads we price on this page. The real bill also depends on how many reasoning tokens each model writes.
Which has the larger context window?
Claude Opus 5.5 reads up to 1,000,000 tokens and can write up to 128,000; Gemini 4 Argon reads up to 1,048,576 and writes up to 943,718.
How much does a support chatbot cost on each model?
For 10,000 conversations a month (about 15 million input and 4 million output tokens) you would pay about $140 on Claude Opus 5.5 and $70 on Gemini 4 Argon at list prices, before any caching or batch discounts.
Do they offer prompt caching or batch discounts?
Claude Opus 5.5 lists cached input at $0.2 per million and a batch rate of $2 / $10. Gemini 4 Argon lists cached input at $0.1 per million and a batch rate of $1 / $5. Caching matters most for agents and chatbots that resend the same context on every turn.
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