Claude Sonnet 5.5

Claude Sonnet 5.5 is an Anthropic model released on September 28, 2026, with the API ID claude-sonnet-5-5.

Lab: Anthropic
Release date: September 28, 2026
Status: Generally available
API model ID: claude-sonnet-5-5
Context window: 1,000,000 tokens
Max output: 128,000 tokens

Anthropic released Claude Sonnet 5.5 on September 28, 2026, as claude-sonnet-5-5. Anthropic’s model docs list a 1M-token context window, 128K max output tokens, text and image input with text output, and a June 2026 knowledge cutoff. It is available in the Claude apps and on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry. Our coverage: Anthropic releases Claude Sonnet 5.5.

Modalities: Text and image input; text output
Knowledge cutoff: June 2026
Availability: Claude apps; 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 Sonnet 5.5 released?

Anthropic released Claude Sonnet 5.5 on September 28, 2026, as claude-sonnet-5-5.

What is the context window of Claude Sonnet 5.5?

Anthropic’s model docs list a 1M-token context window and 128K max output tokens.

Where is Claude Sonnet 5.5 available?

In the Claude apps and on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud and Microsoft Foundry.

What is the knowledge cutoff of Claude Sonnet 5.5?

The model docs list a June 2026 knowledge cutoff.

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.