Claude Sonnet 5.5
Language modelCard summarizedThe best combination of speed and intelligence
Overview
Anthropic · 02Sonnet, front
Sonnet 5.5
The best combination of speed and intelligence
- Cost
- $2.00 in
- Context
- 1M
- Input / output
- $2.00 / $10.00
- Max output
- 128K
- Knows up to
- June 2026
- Released
- 28 Sep 2026
Anthropic's latest Sonnet-class large language model. It significantly outperforms Claude Sonnet 5 across many domains and in a few areas rivals or exceeds Claude Opus 5.5, but is broadly less capable than Opus 5.5 and crosses no new RSP thresholds. p.2–3
claude-sonnet-5-5- Input / output per 1M
- $2.00 / $10.00
- Context window
- 1M
- Max output
- 128K
- Knows up to
- June 2026
- Reasoning
- Adaptive
- Weights
- Closed
About this card. A model card is the maker's own account of a model: what it's for, how it was trained and tested, and where it falls short. This page condenses Anthropic's System Card: Claude Sonnet 5.5. Every claim carries its source page.