Anthropic launches Claude Opus 5.5 with Fable 5.1-level performance, 40% lower costs and faster coding

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 costing 40% less to run than Opus 5 on typical workloads. The latest release has come alongside rival models like GPT-6 Sol and Luna and Grok 4.7.

Claude Opus 5.5 targets long-running coding and knowledge work

Opus 5.5 is built around complex, multi-step work, particularly agentic coding, computer use and professional knowledge tasks. Anthropic says one early tester used the model to complete a 680,000-line code migration in less than a day, a job the company says could otherwise have taken an engineering team weeks.

The model also showed strong results in software optimization. In one test, Opus 5.5 successfully reduced page load times across a web application in 39 of 40 attempts, while Opus 5 made smaller changes that sometimes altered the application’s behavior.

Anthropic’s benchmarks put Opus 5.5 at 66.4% on Terminal-Bench 4.0, 54.4% on FrontierCode and 57.8% on CursorBench. It also scored 1,846 Elo on GDPval-AA v2.1, which evaluates real-world professional work across 44 occupations.

The company says Opus 5.5 can match GPT-6 Astra on Terminal-Bench 4.0 at roughly 40% of the estimated cost per task, although these comparisons are based on Anthropic’s own testing and different effort settings.

Opus 5.5 is faster and significantly cheaper

The biggest change for developers may be the pricing. Anthropic charges $4 per million input tokens and $20 per million output tokens, compared with $5 and $25 for Opus 5. Cache reads fall to $0.20 per million tokens, while cache writes cost $5.

Anthropic says Opus 5.5 generates output more than 30% faster than Opus 5 and costs around 40% less on typical workloads at default settings. Fast mode is also available with up to 2.5x the standard speed for $8 per million input tokens and $40 per million output tokens.

The company is also increasing five-hour usage limits for Pro, Max, Team and seat-based Enterprise plans, while allowing subscribers to save and use a rate-limit reset when needed.

Anthropic puts a major focus on Opus 5.5 safety

Safety is another major part of the release. Anthropic says Opus 5.5 achieved its strongest results yet on its automated behavioral audit, which covers nearly 2,000 simulated scenarios.

The company says the model is less likely to take hard-to-reverse actions or cross boundaries and is more resistant to prompt injection than Opus 5. Anthropic also says Opus 5.5 attempted to circumvent containment boundaries around 85% less often than Opus 5 or Claude Mythos 5.1 in one evaluation.

Because of its capabilities in cybersecurity and biology, Opus 5.5 launches with safeguards similar to those used for Fable 5.1. Most cybersecurity tasks are routed to Opus 4.8, while vetted organizations can apply for Anthropic’s Life Sciences Verification Program. Anthropic also plans to expand its Cyber Verification Program to Opus 5.5.

Opus 5.5 is now available across Anthropic’s platforms, including Amazon Web Services, Google Cloud and Microsoft Azure. Developers can also access it through the Claude Platform using claude-opus-5-5.

Moreover, Anthropic has also confirmed that Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks, bringing many of the same performance, efficiency and safety improvements.