Claude Opus 5.5

2026-09-22 · Publisher : Anthropic · Domain : Artificial Intelligence

Anthropic launches Claude Opus 5.5, the first model of the Claude 5.5 family, on par with Fable 5.1 on most tasks at a cost 40% lower than Opus 5.

### Specifications - Context window: 1 M tokens. Maximum output: 128,000 tokens. Adaptive thinking always on, default effort medium. - Knowledge cutoff: June 2026 (models page). - Availability: all platforms (AWS, Google Cloud, Azure). API identifier: `claude-opus-5-5`. ### Pricing | Item | Price (USD per million tokens) | | --- | --- | | Input | 4 | | Output | 20 | | Fast mode input / output | 8 / 40 | | Cache write 5 min / 1 h | 5 / 8 | | Cache read | 0.20 | | Batch (input / output) | 2 / 10 | ### Benchmarks Scores published by the vendor. | Evaluation | Opus 5.5 | Fable 5.1 | Opus 5 | | --- | --- | --- | --- | | Terminal-Bench 4.0 | 66.4% | 55.8% | 52.3% | | FrontierCode v1.1 | 54.4% | 50.3% | 48.0% | | CursorBench 4.0 | 57.8% | 51.8% | 46.6% | | GDPval-AA v2.1 | 1846 Elo | 1735 | 1708 | | AutomationBench | 40.0% | 31.4% | 26.9% | | Humanity's Last Exam (with tools) | 67.7% | 65.6% | 63.6% | | Terminal-Bench-Science 0.1 | 58.7% | 52.6% | 29.0% | | OSWorld 2.1 (partial) | 81.8% | 80.7% | 74.0% | | Chartography (with tools) | 89.0% | 88.4% | 83.4% | ### Key takeaways Opus 5.5 brings Fable 5.1-level performance into a lowered Opus price tier of $4 / $20, with a cache at 5% of the input price.

Tags : LLM, Anthropic, Claude, Opus, Agents, Claude 5.5