Anthropic releases Claude Sonnet 5.5
Anthropic's Claude Sonnet 5.5 comes close to Opus 5.5 on several coding and knowledge-work benchmarks, keeps Sonnet 5's per-token pricing and runs more than 30% faster than it.
Anthropic has released Claude Sonnet 5.5, the second model in its Claude 5.5 family. The company presents it as a faster, cheaper complement to Claude Opus 5.5, aimed at well-scoped everyday tasks, bug fixing, and producing documents, slides and spreadsheets.
The biggest gain is in agentic coding. Sonnet 5.5 scores 70.6% on Terminal-Bench 4.0, up from 10.3% for Sonnet 5. Opus 5.5's listed score on the same benchmark is 66.4%, with a footnote. On CursorBench 4.0, Sonnet 5.5 scores 55.5%, against 34.1% for Sonnet 5 and 57.8% for Opus 5.5. On GDPval-AA, which covers real-world tasks across 44 occupations, it scores 1844, compared with 1846 for Opus 5.5 and 1449 for Sonnet 5. Anthropic also reports 80.1% on OSWorld 2.1 and 64.5% on Humanity's Last Exam with tools.
Anthropic says benchmarks don't tell the whole story. In its testing and that of external testers, Opus 5.5 "remains clearly stronger at complex, open-ended work requiring sustained judgment."
Pricing is unchanged from Sonnet 5, per million tokens:
- $2 for input
- $10 for output
- $0.20 for cache reads
Anthropic says the model uses fewer tokens per task, so it costs up to 30% less per task than Sonnet 5. It also generates output more than 30% faster. On FrontierCode at High effort, Anthropic says Sonnet 5.5 scores 10 points above Sonnet 5 at about one-fifteenth of the cost per task.
Anthropic rates the model's cybersecurity capabilities as comparable to Opus 5's. That makes it the first Sonnet model to ship with cyber safeguards and fallbacks. Its biology safeguards are the same as Sonnet 5's.
Anthropic says Claude Haiku 5.5 will follow in the coming weeks. Full evaluation details are in the Sonnet 5.5 System Card.