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Claude Sonnet 5.5

Above Opus 5.5 on Terminal-Bench, at half the input price.

currentAnthropic ↗Verified 2026-09-29

$2

per M input

Specifications

Context1Msource · as of 2026-09-29
Input ($/Mtok)$2source · as of 2026-09-29
Output ($/Mtok)$10source · as of 2026-09-29
LicenceProprietarysource · as of 2026-09-29
Max output128Ksource · as of 2026-09-29
ParametersNot publishedsource · as of 2026-09-29
Released28 Sep 2026source · as of 2026-09-29
Model IDclaude-sonnet-5-5source · as of 2026-09-29

Official links

Claude Sonnet 5.5 model pageAnthropic official site

What matters

  • 70.6% on Terminal-Bench 4.0, against 66.4% for Opus 5.5 six days earlier
  • 1844 on GDPval-AA, level with Opus 5.5's 1846
  • More than 30% faster than Sonnet 5, and Anthropic says up to 30% less per task on tokens

Best for agentic coding at volume.

Compare with

All 5 side by side →

Claude Sonnet 5.5 vs GPT-6 Astra →Claude Sonnet 5.5 vs Claude Fable 5.1 →Claude Sonnet 5.5 vs Claude Fable 5 →Claude Sonnet 5.5 vs Claude Opus 5.5 →Claude Sonnet 5.5 vs GPT-6.1 Sol →

Also in Language Models

GPT-6 Astra · OpenAIClaude Fable 5.1 · AnthropicClaude Fable 5 · AnthropicClaude Opus 5.5 · AnthropicGPT-6.1 Sol · OpenAI