Claude Sonnet 5 Launched with 1M Token Context, New Tokenizer
Anthropic has launched Claude Sonnet 5, featuring a 1 million token context window and a new tokenizer that increases token count by approximately 30%. This release impacts users migrating from Sonnet 4.6 due to changes in adaptive thinking and the removal of manual extended thinking. Sonnet 5 is available at introductory pricing until August 31, 2026, with Priority Tier support not included.
- →Launch Claude Sonnet 5 with 1M token context window
- →Behavior changes for Claude Sonnet 5 migration
- →Manual extended thinking removed in Sonnet 5
- →Introductory pricing and availability
Breaking changes (1) ›
- Behavior changes for Claude Sonnet 5 migration
Migrating to Sonnet 5 requires adapting to changes including adaptive thinking enabled by default and the removal of manual extended thinking. Non-default sampling parameters will now return a 400 error.
Deprecations (1) ›
- Manual extended thinking removed in Sonnet 5
Manual extended thinking functionality (`thinking: {type: "enabled", budget_tokens: N}`) has been removed in Claude Sonnet 5. This feature was previously deprecated on Sonnet 4.6 and will now return a 400 error.
Features (1) ›
- Launch Claude Sonnet 5 with 1M token context window
The new Claude Sonnet 5 model offers a 1 million token context window and 128k max output tokens. It supports the same platform features as Sonnet 4.6, excluding Priority Tier.
Notes (1) ›
- Introductory pricing and availability
Claude Sonnet 5 is available at introductory pricing of $2/10 per MTok until August 31, 2026, after which standard pricing of $3/15 per MTok will apply. Priority Tier is not available for Sonnet 5.
https://platform.claude.com/docs/en/release-notes/overview