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Pyyan / Compare / Claude Sonnet 5 vs Claude Fable 5.1

Claude Sonnet 5 vs Claude Fable 5.1

2 of 5

Language Models · verified 2 Sept 2026

Claude Sonnet 5Anthropiccurrent
Claude Fable 5.1Anthropiccurrent
3 slots left
SpecificationClaude Sonnet 5Claude Fable 5.1
SummaryNear-Opus quality on coding and agentic work at Sonnet cost.Same price as Fable 5, and cache reads cost a quarter of what they did.
Context1M1M
Input ($/Mtok)$3$10
Output ($/Mtok)$15$50
LicenceProprietaryProprietary
Max output128K128K
Parameters—Not published
Released—1 Sep 2026
Model IDclaude-sonnet-5claude-fable-5-1
CategoryLanguage ModelsLanguage Models
OfficialAnthropic ↗—

Highlighted rows are where these differ.

Claude Sonnet 5

  • Adaptive thinking on by default
  • New tokenizer — roughly 30% more tokens for the same text
  • Introductory $2/$10 through 31 Aug 2026

Best for high-volume production.

Full spec sheet →

Claude Fable 5.1

  • Matches or beats Fable 5 at low and medium effort, and pulls clear at high effort
  • Cache reads cut to 25% of the old price, so re-reading a long context got much cheaper
  • Identical model to Mythos 5.1 underneath; the difference is the safeguards

Best for coding and long-running work.

Full spec sheet →