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Pyyan / Compare / Claude Opus 5 vs Claude Fable 5.1

Claude Opus 5 vs Claude Fable 5.1

2 of 5

Language Models · verified 2 Sept 2026

Claude Opus 5Anthropiccurrent
Claude Fable 5.1Anthropiccurrent
3 slots left
SpecificationClaude Opus 5Claude Fable 5.1
SummaryComplex agentic coding and enterprise work at half the cost of Fable 5.Same price as Fable 5, and cache reads cost a quarter of what they did.
Context1M1M
Input ($/Mtok)$5$10
Output ($/Mtok)$25$50
LicenceProprietaryProprietary
Max output128K128K
Parameters—Not published
Released24 Jul 20261 Sep 2026
Model IDclaude-opus-5claude-fable-5-1
CategoryLanguage ModelsLanguage Models
OfficialAnthropic ↗—

Highlighted rows are where these differ.

Claude Opus 5

  • Thinking on by default — a step change over Opus 4.8
  • 512-token prompt-cache minimum, down from 1024
  • Separate rate-limit bucket from the Opus 4.x pool

Best for agentic coding.

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 →