Models & research

Anthropic's Claude Sonnet 5.5 is faster and cheaper per task, and beats its flagship on one benchmark

Anthropic released Claude Sonnet 5.5 on 28 September 2026. It runs more than 30% faster than Sonnet 5 and costs up to 30% less for most work, at the same per-token price. On Anthropic's own benchmarks it beats the flagship Opus 5.5 on one agentic test, though independent evaluations are not in yet.