Models

Claude Sonnet 4.5

Anthropic · September 2025

An earlier Sonnet for writing and code. Reads a fifth of what 4.6 and later hold.

Superseded by Claude Sonnet 4.6 →

  • Modalities

  • Context window

    200,000 tokens, ≈ 150,000 words · about 600 pages

  • Max output

    64,000 tokens, ≈ 48,000 words in a single answer

  • Knowledge cutoff

    January 2025

Providers

Files you can attach

  • ImagesJPG, PNG, GIF, WEBP
  • DocumentsPDF
  • Text and codeTXT, MD, CSV, TSV, RPT, LOG, PY, TS, TSX, JS, JSX, CS, GO, JAVA, KT, SWIFT, CPP, C, H, PHP, RB, SQL, SH, PS1, HTML, CSS, SCSS, JSON, YAML, YML, XML, INI

Tools

  • Web searchSupported
  • Code interpreterSupported

Features

  • StreamingSupported
  • Function callingSupported
  • Structured outputsSupported
  • Fine-tuningNot supported

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