Claude Sonnet 5.5 launch
By Steven Van ·
Sonnet 5.5 keeps Sonnet 5's per-token prices, scores 70.6% on Terminal-Bench 4.0, and Haiku 5.5 is due in the coming weeks.
Sonnet 5.5 is out, and it runs 30% or more faster than Claude's previous Sonnet while costing up to 30% less per task for most work, according to Anthropic's announcement. It is the second model in the Claude 5.5 family and is positioned as a faster, lower-cost complement to Opus 5.5.
Pricing per token is unchanged from Sonnet 5: $2 per million input tokens, $10 per million output tokens and $0.20 per million tokens for cache reads. The saving comes from the model typically needing far fewer tokens to do the same work.
Anthropic says Sonnet 5.5 is strongest at well-scoped everyday tasks, fixing bugs, and producing polished documents, slides and spreadsheets. Early testers also pointed to its handling of design, including polish on user interfaces and following slide templates. Opus 5.5 remains the pick for complex, open-ended work that needs sustained judgment.
- Terminal-Bench 4.0, an agentic coding test: 70.6%, against 10.3% for Sonnet 5.
- CursorBench 4.0: 55.5%, against 34.1% for Sonnet 5 and 57.8% for Opus 5.5.
- Medium effort is the default in the Claude apps, and High effort is the default on the Claude Platform.
It is the first Sonnet model to launch with cyber safeguards and fallbacks like those on Anthropic's most capable models. Anthropic says these target a narrow set of high-risk requests, and that routine software development is unaffected. Claude Haiku 5.5, for high-volume and cost-sensitive uses, is due in the coming weeks.
