Claude Sonnet 5.5

Changes from previous version

Successor to Claude Sonnet 5 at the same $2/$10 list rates. Terminal-Bench 4.0 rises from 10.3% to 70.6%, CursorBench 4.0 from 34.1% to 55.5%, and GDPval-AA v2.1 from 1449 to 1844. Anthropic reports fewer tokens on typical tasks, up to 30% lower cost per task, and more than 30% faster output. Max effort is much more expensive on measured price per task ($7.60 versus $1.72) because it spends far more output tokens. High effort, the API default, is $1.08 per task.

Release Summary

Second model in the Claude 5.5 family, and a faster complement to Claude Opus 5.5 for well-scoped everyday tasks, bug fixes, and polished documents, slides, and spreadsheets. Scores 70.6% on Terminal-Bench 4.0, versus 10.3% for Claude Sonnet 5 and 66.4% for Opus 5.5 at xhigh. CursorBench 4.0 is 55.5% (Opus 5.5 is 57.8%). GDPval-AA v2.1 is 1844 Elo, two points below Opus 5.5. FrontierCode v1.1 Main is 52.1% at xhigh and 46.2% at max. List price stays $2/M input and $10/M output, with $0.20/M cache reads and $2.50/M cache writes. Anthropic reports up to 30% lower cost per task than Sonnet 5 and output that is more than 30% faster. A measured price per task is $7.60 at max effort and $1.08 at high effort, the Claude Platform default. Apps default to medium. Available as claude-sonnet-5-5 on the Claude Platform, Amazon Web Services, Google Cloud, and Microsoft Azure. 1M-token context, 128k max output, knowledge cutoff June 2026. First Sonnet with cyber safeguards and reasoning-extraction classifiers comparable to Opus 5.5. Thinking cannot be turned fully off: use between_tools to keep up-front thinking off. Claude Haiku 5.5 is still scheduled for the coming weeks.

Timeline

Other Claude Sonnet versions