Anthropic · Claude Opus 5.5

Claude Opus 5.5

Released 22 September at $4 and $20 per million input and output tokens, $0.20 for cache read and $5 for cache write, with a faster mode at $8 and $40. Anthropic states it costs 40% less to run than Opus 5 on typical workloads while generating output over 30% faster. Its own benchmark table shows gains over Opus 5 and named competitors Fable 5.1, GPT-6 Astra and GPT-5.6 Sol: 66.4% on Terminal-Bench 4.0 against Opus 5's 52.3%, 67.7% on Humanity's Last Exam with tools against 63.6%, and 81.8% on OSWorld 2.0 against 74.0%. Anthropic also states it attempted to circumvent boundaries around 85% less often than Opus 5. Available on the Claude Platform, AWS, Google Cloud and Azure across Pro, Max, Team and Enterprise. Parameter count and context window are not disclosed.