AI models · Anthropic

Claude Opus 5.5

Claude Opus 5.5 is the model Anthropic recommends starting with for most demanding tasks. It ranks second of 52 models on the independent Artificial Analysis index, and when the AI works on its own in a terminal, Anthropic says it beats the pricier Fable 5.1. It handles 1 million tokens at once, which is hundreds of pages. It suits companies and individuals who want the AI to do real work on its own, not just give short answers.

Strengths

  • It scores 58 on the Artificial Analysis Intelligence Index v5.0, second of 52 models, just ahead of GPT-6 Astra (57).
  • For coding in a terminal, Anthropic reports 66.4% on Terminal-Bench 4.0, compared with 57.9% for GPT-6 Astra and 55.8% for Fable 5.1.
  • It beats Fable 5.1 on most benchmarks Anthropic published, yet costs 60% less: $4 input and $20 output per million tokens.
  • The full 1M-token window comes with no long-input surcharge. Input and output are 20% cheaper than on Opus 5.
  • Anthropic says it resists hidden instructions planted in documents or web pages (prompt injection) better than Opus 5.

Weaknesses

  • It is very wordy. It used 220 million output tokens on the Artificial Analysis tests, so the cost per task came to $10.04, 49th of 51.
  • It always thinks before answering and you cannot turn that off. Forcing tool use through the API returns an error, which can break some older integrations.
  • Safety filters reroute most cybersecurity tasks to the older Opus 4.8. Biology research may require Anthropic's verification program.
  • It is not available on the free Claude plan.

Best for

  • Coding where the AI takes many steps on its own
  • Long-running knowledge work with information and documents
  • Analyzing very long documents in one go
  • Controlling a computer or a browser
  • Default choice for demanding business tasks

Not ideal for

  • High volumes of cheap classification or data extraction
  • Chat where an instant reply matters
  • Offensive security testing, safety filters reroute it

How to use it in Europe

In Europe you can use it in the Claude app on the web, desktop and mobile with a Pro, Max, Team or Enterprise plan. It is not on the free plan. Developers call it through the Anthropic API or through Amazon Bedrock, Google Cloud and Microsoft Foundry. Slovakia and Czechia are supported countries. A note for companies: the direct API processes data globally or in the US and stores it in the US, with no EU region to choose.

Price compared with similar models

1 3 10 30 Beam 1.01 Mistral Large 31.5 DeepSeek V4 Pro3.96 Mistral Large 44.18 Qwen3.8-Max6 Qwen3.8-2.4T-A95B6 Grok 4.76 Gemini 4 Carbon10 Gemini 4 Argon10 Kimi K3.1 Pro10 Kimi K315 Claude Opus 5.520 Muse Wonder20 GPT-6 Astra50
Output price in USD per 1M tokens (log scale). Lighter bars are open-weight models.

Benchmark results

BenchmarkScoreSource
Artificial Analysis Intelligence Index v5.0 (max effort)58 (#2 of 52)artificialanalysis.ai ↗, October 2026
Terminal-Bench 4.066.4%anthropic.com ↗ (vendor-reported), September 2026
GDPval-AA v2.1 Elo1846anthropic.com ↗ (vendor-reported), September 2026
Humanity's Last Exam, with tools67.7%anthropic.com ↗ (vendor-reported), September 2026
OSWorld 2.1 partial81.8%anthropic.com ↗ (vendor-reported), September 2026

Benchmarks cover only a narrow slice of ability and vendors often report them at their best settings. Treat them as a rough guide.

More models from this vendor

  • Claude Fable 5.1: Claude's most expensive model, meant for the hardest tasks and long autonomous work when even Opus 5.5 falls short.
  • Claude Sonnet 5.5: Claude's balanced model for everyday work and coding. It is faster than Opus 5.5 and costs half as much.
  • Claude Haiku 5.5: Claude's cheapest and fastest model, built for classification, data extraction and large volumes of simple tasks.

Similar models from other vendors

  • DeepSeek V4 Pro (DeepSeek): DeepSeek's largest open-weight model for demanding text tasks at a low price. It does not understand images.
  • Gemini 4 Carbon (Google): Google's most capable model, announced on 28 October 2026. So far only selected cybersecurity experts have access.
  • Gemini 4 Argon (Google): Google's most capable publicly available model, out in October 2026. Built for demanding analytical work where accuracy matters and made-up answers are costly.
  • Muse Wonder (Meta): Meta's strongest model for long-running agents and coding, still released as a preview.
  • Mistral Large 4 (Mistral AI): Mistral's largest model, still in preview. Built for demanding tasks, long documents and security analysis with data kept in the EU.
  • Mistral Large 3 (Mistral AI): Mistral's previous large model with open weights under Apache 2.0. Cheap in the API and suited to your own powerful server.

Sources

Prices and models change often. The data comes from official vendor pricing pages and documentation, and every page shows when it was last checked. Before a larger purchase, confirm the price with the vendor.

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