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Pyyan / Compare / Claude Fable 5 vs Claude Sonnet 5.5

Claude Fable 5 vs Claude Sonnet 5.5

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Language Models · verified 29 Sept 2026

Claude Fable 5Anthropiccurrent
Claude Sonnet 5.5Anthropiccurrent
3 slots left
SpecificationClaude Fable 5Claude Sonnet 5.5
SummaryMost capable widely released model, for the hardest reasoning and long-horizon agentic work.Above Opus 5.5 on Terminal-Bench, at half the input price.
Context1M1M
Input ($/Mtok)$10$2
Output ($/Mtok)$50$10
LicenceProprietaryProprietary
Max output128K128K
Parameters—Not published
Released—28 Sep 2026
Model IDclaude-fable-5claude-sonnet-5-5
CategoryLanguage ModelsLanguage Models
OfficialAnthropic ↗Anthropic ↗

Highlighted rows are where these differ.

Claude Fable 5

  • Thinking is always on — the `thinking` param is rejected
  • Raw chain of thought is never returned
  • Requires 30-day data retention; unavailable under ZDR

Best for the hardest problems.

Full spec sheet →

Claude Sonnet 5.5

  • 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.

Full spec sheet →