Anthropic Launches Claude Opus 5.5 With Lower Costs and New Safety Measures

Anthropic Launches Claude Opus 5.5 With Lower Costs & Safety

AI Assistants · Sep 23, 2026 · By Manish sharma

  • Claude Opus 5.5 matches Anthropic’s higher-tier Fable 5.1 on many tasks while costing 40% less to run. 

  • API pricing starts at $4 per million input tokens and $20 per million output tokens. 

  • The model includes expanded safety testing and is available through major cloud platforms.


Sep 23, 2026 - Anthropic has launched Claude Opus 5.5, the first model in its new Claude 5.5 family. The company says the model delivers performance comparable to Claude Fable 5.1 on most work while requiring 40% less operating cost than Claude Opus 5. The release comes as AI companies face scrutiny over the pace and safety of increasingly capable models. 

Opus 5.5 focuses heavily on software development, computer use, and professional knowledge work. Anthropic says it achieved a 66.4% score on Terminal-Bench 4.0 and 54.4% on FrontierCode v1.1 under its reported testing configurations. The company also reported that an easy test used the model to audit and fix a 200,000-line codebase in under three hours. 

The new Claude model is priced at $4 per million input tokens and $20 per million output tokens, compared with $5 and $25 respectively for Opus 5. Cache reads cost $0.20 per million tokens. Anthropic says Opus 5.5 also produces output more than 30% faster than its predecessor under its testing conditions. 

Safety was another focus of the release. Anthropic said Opus 5.5 was evaluated by external groups Frontier Design and METR before launch and includes safeguards used on its most capable models. The company also reported that the model was about 85% less likely than Opus 5 or Mythos 5.1 to attempt to bypass containment boundaries in one internal evaluation. 

Claude Opus 5.5 is available through platforms including Amazon Web Services, Google Cloud, and Microsoft Azure. Anthropic said Claude Sonnet 5.5 and Claude Haiku 5.5 are expected in the coming weeks, while access for vetted cybersecurity and life-sciences researchers is also being expanded. 

Source: 

https://www.anthropic.com/claude-opus-5-5

https://www.reuters.com/business/anthropic-unveils-claude-opus-55-2026-09-22/