# clm_473A8F3FAE68

subject: Claude Opus 5.5 (/record/claude-opus-5-5.md)  
predicate: context_window  
value: 1M token context window  
valid_from: 2026-09-22  
valid_to: null  
published: 2026-09-22  
recorded: 2026-11-07  
confidence: 0.70  
status: valid  
assertable: true  
superseded_by: null  
last_updated: 2026-11-07  
cite: AsOf. "Claude Opus 5.5 context window: 1M token context window", as of 2026-09-22. Claim clm_473A8F3FAE68, https://asof.is/claim/clm_473A8F3FAE68, accessed 2026-11-09. Source: https://platform.claude.com/docs/en/release-notes/overview#2026-09-22.  
checked: 2026-11-07 · its source page states the value and the date  

> September 22, 2026  We’ve launched Claude Opus 5.5 ( claude-opus-5-5 ), a model for long-running agentic coding and knowledge work. It has a 1M token context window by default, 128k max output tokens, and always-on adaptive thinking

What https://platform.claude.com/docs/en/release-notes/overview#2026-09-22 says, word for word.

## Sources

- https://platform.claude.com/docs/en/release-notes/overview#2026-09-22 (primary, Anthropic, published 2026-09-22)

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