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Anthropic launches Opus 5.5 with Fable level performance at 40% lower cost
Claude Opus 5.5 undercuts its predecessor by 20% as the AI safety company eyes a public listing that could value it above $1 trillion
Anthropic has launched Claude Opus 5.5, its latest flagship model for coding and knowledge work, with lower costs and stronger performance across several professional benchmarks.
Opus 5.5 is the first model in Anthropic’s new Claude 5.5 family. The company said it performs at roughly the level of Claude Fable 5.1 on most work while costing 40% less to run on typical workloads than Opus 5.
The model costs $4 per million input tokens and $20 per million output tokens, both 20% below Opus 5. Cached reads have fallen 60% to $0.20 per million tokens, while output generation is more than 30% faster.
Anthropic reported substantial gains in agentic coding. Opus 5.5 scored 66.4% on Terminal Bench 4.0, compared with 52.3% for Opus 5 and 57.9% for GPT 6 Astra. It also scored 57.8% on CursorBench 4.0 and 54.4% on FrontierCode 1.1.
The company said Opus 5.5 is particularly suited to long running software tasks. One early tester completed a 680,000 line code migration in less than a day, while another used the model to audit and repair a 200,000 line codebase in under three hours.
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Anthropic also emphasized improvements in knowledge work. Opus 5.5 scored 1,846 Elo on GDPval AA 2.1, ahead of Fable 5.1 at 1,735 and Opus 5 at 1,708. The benchmark measures professional tasks across 44 occupations.
The release is Anthropic’s first since CEO Dario Amodei called for pacing frontier AI development. Opus 5.5 underwent external evaluation by METR and Frontier Design, while Anthropic said the model achieved its strongest results yet on its internal behavioral alignment audit.
The model also introduces stronger safeguards for cybersecurity, biology and model distillation. Anthropic said Opus 5.5 attempted to cross containment boundaries about 85% less often than Opus 5 or Claude Mythos 5.1 in one internal evaluation.
Claude Opus 5.5 is available across Anthropic’s platforms as well as Amazon Web Services, Google Cloud and Microsoft Azure. Claude Sonnet 5.5 and Claude Haiku 5.5 are expected to follow in the coming weeks.