Claude Opus 5.5 brings a larger context window at lower cost

Claude Opus 5.5 is Anthropic’s first model in the Claude 5.5 family, released on September 22, 2026. The proprietary model accepts text and image input, returns text output, and targets long-running agentic coding and knowledge work.

The model performs at Claude Fable 5.1 level on most work at about 40% lower cost than Claude Opus 5. Pricing via Anthropic starts at $4.00 per million input tokens and $20.00 per million output tokens, with reused prompt prefixes priced at $0.200 per million cached input tokens.

Claude Opus 5.5 has a 1M-token context window, with output limits shown as 128Ktokens. Live usage over the trailing 7 days shows p95 time to first token of 8.47 seconds via Anthropic, while the model’s speed section lists throughput at 15.8char/s.

Hosted access is available through Anthropic under product and API terms. The model is proprietary and has a knowledge cutoff of June 2026, with official resources including provider documentation, the Claude playground, a system card, and a launch post.