Claude Sonnet 4.5 (deprecated)
Claude Sonnet 4.5 is a deprecated Anthropic model scheduled for retirement on November 30, 2026.
- Lab
- Anthropic
- Release date
- Status
- Deprecated
- API model ID
- claude-sonnet-4-5-20250929
- Shutdown date
Anthropic announced the deprecation of Claude Sonnet 4.5 (claude-sonnet-4-5-20250929) on September 30, 2026. Retirement is scheduled for November 30, 2026, and Anthropic recommends migrating to Claude Sonnet 5.5. Until retirement, the model remains available on the Claude API.
- Availability
- Claude API until retirement. Recommended replacement: Claude Sonnet 5.5.
- Official source
- platform.claude.com
- Last checked
Questions
When will Claude Sonnet 4.5 be retired?
Retirement is scheduled for November 30, 2026, after Anthropic announced the deprecation on September 30, 2026.
What should replace Claude Sonnet 4.5?
Anthropic recommends migrating to Claude Sonnet 5.5.
What is the API ID of Claude Sonnet 4.5?
The model ID is
claude-sonnet-4-5-20250929, available on the Claude API until retirement.Source
Release dates, model IDs and limits come from each lab’s own announcement, changelog, documentation or deprecations page, linked on every model with the date it was last checked. How we pick and check sources: editorial standards.