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Claude Sonnet 4.5

Deprecated · Language, Multimodal, Reasoning

Claude Sonnet 4.5 is a language model in Anthropic's Sonnet line that accepts text and images, with a 200K-token context window and an extended thinking mode. It is offered in the Claude apps, on the Anthropic API, Amazon Bedrock and Google Cloud Vertex AI, and Anthropic presents it as a drop-in replacement for Claude Sonnet 4 at the same price. [1]Capabilities [2] [3]Claude Sonnet 4.5 Summary Table, Access Surfaces Primary source

Timeline of Claude Sonnet 4.5 →

Claims and evidence

  • Released Primary source[2] [4]September 29, 2025 [1]Availability
  • Deprecated Primary source[5]2026-09-30: Claude Sonnet 4.5 model [4]September 30, 2026
  • Status DeprecatedRetirement on the Claude API is scheduled for 2026-11-30. Primary source[5]Model status [1]Availability
  • Replaced by Claude Sonnet 5.5Recommended replacement as listed on the deprecations page when checked on 2026-10-01. Primary source[5]2026-09-30: Claude Sonnet 4.5 model
  • Change · Safety Released under the ASL-3 Standard, with classifiers aimed at CBRN-related content; Claude Sonnet 4 was released under ASL-2.Compared with Claude Sonnet 4 Primary source[6] [2] [7]
  • Change · Training data Training data includes public web data as of July 2025, against March 2025 for Claude Sonnet 4.Compared with Claude Sonnet 4 Primary source[6] [7]
  • Input text, image Primary source[1]Capabilities [3]Claude Sonnet 4.5 Summary Table, Modalities
  • Output text Primary source[1]Capabilities
  • Feature Reasoning mode Primary source[1]Capabilities [6]section 1.1.2
  • Context window 200K tokensA 1M-token context window was offered in beta (release notes 2026-02-05 and earlier); that beta was retired for this model on 2026-04-30 (release notes 2026-03-30). Primary source[1]Capabilities
  • Parameters Not disclosedNot disclosed by Anthropic. No claim madeNo source
  • Access consumer app, API, cloud partner Primary source[2] [3]Claude Sonnet 4.5 Summary Table, Access Surfaces

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None recorded.

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