Anthropic ships Sonnet 5.5, tops Opus 5.5 on coding bench

Anthropic released Claude Sonnet 5.5 today at the same token prices as Sonnet 5 — $2 per million input tokens, $10 per million output tokens — and the mid-tier model beat its own flagship on an agentic coding benchmark.

On Terminal-Bench 4.0, Sonnet 5.5 scored 70.6% against Sonnet 5's 10.3%. It also exceeds Opus 5.5's reported 66.4% on the same evaluation. On GDPval-AA, drawn from real-world occupations, Sonnet 5.5 scores 1844; Opus 5.5 scores 1846.

Anthropic frames Sonnet 5.5 as "a faster, lower-cost complement to Claude Opus 5.5," "strongest at well-scoped everyday tasks, fixing bugs, and producing polished documents, slides, and spreadsheets." The company says the model runs more than 30% faster than Sonnet 5 and costs up to 30% less per task in its own testing.

Epic Games ran the model on a system design audit and a data flow review across tens of thousands of lines of gameplay system architecture code, and reported that it "held the quality bar expected from a higher-tier model." Sonnet 5.5 is available on AWS, Google Cloud, and Microsoft Azure under the model ID claude-sonnet-5-5, with a June 2026 knowledge cutoff. Claude Haiku 5.5 is expected in the coming weeks.