Claude Opus 5.5

Claude Opus 5.5 is an Anthropic model released on September 22, 2026, with the API ID claude-opus-5-5.

Lab: Anthropic
Release date: September 22, 2026
Status: Generally available
API model ID: claude-opus-5-5
Context window: 1,000,000 tokens
Max output: 128,000 tokens

Anthropic released Claude Opus 5.5 on September 22, 2026, as claude-opus-5-5. The release notes give a 1M-token context window by default and 128K max output tokens, with always-on adaptive thinking; the model docs list text and image input with text output and a June 2026 knowledge cutoff. It is available on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry.

Anthropic raised five-hour usage limits on Pro, Max, Team and seat-based Enterprise plans with the launch. Our coverage: Anthropic releases Claude Opus 5.5.

Modalities: Text and image input; text output
Knowledge cutoff: June 2026
Availability: Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, Microsoft Foundry.
Official source: anthropic.com
Last checked: October 5, 2026

Questions

When was Claude Opus 5.5 released?

Anthropic released Claude Opus 5.5 on September 22, 2026, as claude-opus-5-5.

What is the context window of Claude Opus 5.5?

The release notes give a 1M-token context window by default and 128K max output tokens.

What is the knowledge cutoff of Claude Opus 5.5?

Anthropic’s model docs list a June 2026 knowledge cutoff, with text and image input and text output.

Did Claude Opus 5.5 change usage limits?

Yes. Anthropic raised five-hour usage limits on Pro, Max, Team and seat-based Enterprise plans with the launch.

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.