From the source
Anthropic launched Claude Sonnet 5.5 on September 28, positioning it close to Opus 5.5 on several tests at half Opus's input and output token prices.
- At maximum effort, Artificial Analysis gave Sonnet 5.5 a score of 56 on its Intelligence Index, behind only Opus 5.5 at 58.
- Anthropic prices Sonnet at $2 per million input tokens and $10 per million output tokens, compared with Opus's $4 and $20, and claims output is at least 30% faster than Sonnet 5 with task costs up to 30% lower.