Claude Opus 5.5 Fast

Anthropic's Claude Opus 5.5 launched September 22, 2026 with a Fast mode research preview that delivers the same model output at up to 2.5x speed, priced at $8 per million input tokens and $40 per million output tokens versus the standard $4/$20. The base model already generates output 30% faster than Claude Opus 5 before Fast mode is enabled. Fast mode requires extra usage to be activated and is invoked in Claude Code with the /fast command, making it suited to interactive sessions rather than long autonomous runs. Anthropic also raised five-hour usage limits across Pro, Max, Team, and Enterprise plans alongside the launch, and added a user-triggerable rate-limit reset for in-progress tasks.

Claude Opus 5.5 launched September 22, 2026 with the API ID claude-opus-5-5, scoring 66.4% on Terminal-Bench 4.0 and generating output 30% faster than Claude Opus 5 at roughly 40% lower pricing once cache savings are counted. A 2.5x Fast mode research preview ships alongside the base model for accounts with extra usage enabled. Anthropic shipped day-one general availability on the Claude Platform, Amazon Web Services, Google Cloud, and Microsoft Azure, including a zero-data-retention option for regulated deployments. Thinking mode can no longer be fully disabled in the new release, and Sonnet 5.5 plus Haiku 5.5 were promised in subsequent weeks.