New release
Claude Sonnet 5.5: faster, same price, one setting changes
Anthropic says Sonnet 5.5 is about 30% faster than Sonnet 5 at the same price. If you turned thinking off in the API, a new setting applies.
- Date
- Works with
- Claude Code
What’s new
Anthropic released Claude Sonnet 5.5 on 28 September 2026. Anthropic says it generates output more than 30% faster than Sonnet 5. The price did not change: $2 per million input tokens and $10 per million output tokens.
The default effort level is Medium in Claude Code and High in the API.
Why it matters
You get a faster model for daily coding work and you pay the same as before.
If you call Sonnet 5 through the API with thinking turned off, your setup needs a change. Sonnet 5.5 has a new setting named between_tools. Anthropic describes it as the way to keep up-front thinking off.
How to try it
In the API, use the model name claude-sonnet-5-5. Read Anthropic's migration guide before you change a setup that has thinking turned off.
Source
Checked against the source on 12 Oct 2026