Introducing Claude Sonnet 5.5, the second model in the Claude 5.5 family. It’s a clear upgrade over Claude Sonnet 5, runs 30%+ faster, and costs up to 30% less for most work. Sonnet 5.5 is a faster, lower-cost complement to Claude Opus 5.5. Where Opus 5.5 is built for complex work requiring careful judgment, Sonnet 5.5 is strongest at well-scoped everyday tasks, fixing bugs, and creating polished documents, slides, and spreadsheets. It’s also got a sharp eye for design. Claude Haiku 5.5 will join the family in the coming weeks.

Sonnet 5.5 improves over Sonnet 5 on performance, scoring 70.6% on Terminal-Bench 4.0, an agentic coding evaluation, compared to Sonnet 5’s 10.3%. It scores two points below Opus 5.5 on GDPval-AA. It’s strong on long-horizon work and image understanding—it’s the first Sonnet model to beat Pokémon Red working only from screenshots. It writes more clearly than previous models, with early testers describing it as a better partner for collaboration.

Sonnet 5.5 is priced the same as Sonnet 5 at $2 per million input tokens, $10 per million output tokens, and $0.20 per million tokens for cache reads, but typically needs far fewer tokens. It costs up to 30% less per task and generates outputs 30%+ faster. On automated behavioral audit, Sonnet 5.5 improves on or matches Sonnet 5 on alignment. It’s the first Sonnet model to launch with cyber safeguards and fallbacks, with biology safeguards unchanged.

On several benchmarks, Sonnet 5.5 at Low or Medium effort beats Sonnet 5’s best score for about a tenth of the cost per task. It complements Opus 5.5 best at lower effort settings, where it costs less per task. At higher settings, it can perform comparably at a similar cost.