Introducing Claude Sonnet 5.5
Anthropic, Monday, September 28th, 2026
Anthropic releases Claude Sonnet 5.5, a faster, cheaper upgrade over Sonnet 5 that complements Opus 5.5.
Anthropic introduced Claude Sonnet 5.5, the second model in the Claude 5.5 family, which runs more than 30% faster than Sonnet 5 and costs up to 30% less for most work.
Sonnet 5.5 targets well-scoped everyday tasks, bug fixing and polished documents, slides and spreadsheets, and scores 70.6% on the Terminal-Bench 4.0 agentic coding evaluation.
Claude Haiku 5.5 is expected to join the family in the coming weeks.