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Anthropic

Claude Fable 5.1

Benchmarks, price, context and versions

Also searched as

Claude-Fable-5.1

Direct answer: Claude Fable 5.1 is a model from Anthropic. 89.9% on GPQA Diamond (OpenRouter), per OpenRouter Benchmarks. On OpenRouter, US$ 10.00 per 1 million input tokens and US$ 50.00 per 1 million output tokens.

✓ Good for

  • calculation and problems with an exact answer (#10 of 186 on OTIS Mock AIME)
  • the ceiling of reasoning on research-level math (#6 of 86 on FrontierMath (tiers 1 to 3))
  • answering short facts with little invention (#7 of 87 on SimpleQA Verified)
  • agents that follow rules and use tools (#7 of 131 on τ-bench Verified (airline))
  • very long documents or code (a window of 1 million tokens or more, according to OpenRouter)

✕ Not the best for

  • when the input budget sits at the top of the table (input price in the highest 25% on OpenRouter)

This block follows a rule of this section, using source data: if the model is in the top 25% of the metric, the item goes under "Good for"; if it is in the bottom half, it goes under "Not the best for". The middle band appears in neither. Price and context use OpenRouter; scores use Epoch AI or OpenRouter Benchmarks, in the latest version we checked.

Benchmarks

FrontierMath (tiers 1 to 3)

?
90.2%

highest score on this metric 95.1%

6º / 86 · Epoch AI, latest version we checked

SimpleQA Verified

?
70.8%

highest score on this metric 94%

7º / 87 · Epoch AI, latest version we checked

GPQA Diamond (OpenRouter)

?
89.9%

highest score on this metric 96.5%

41º / 135 · OpenRouter Benchmarks, latest version we checked

τ-bench Verified (airline)

?
79.2%

highest score on this metric 82%

7º / 131 · OpenRouter Benchmarks, latest version we checked

Key specs

Origin
the US
Family
Claude Fable provisional data
Weights?
closed
License
no data
Input US$/1M?
US$ 10.00
Output US$/1M
US$ 50.00
Context?
1,000,000 tokens
Parameters
no data
Input
file, image, text
OpenRouter usage?
no data
Downloads (30 days)?
no data
Use cases provisional data
Text Agents
Dates in sources
  • 2026, published, per Epoch AI
  • 2026, listed on OpenRouter

Version history

Dates come from the sources: OpenRouter listing or Hugging Face repo creation, which may differ from the official launch.

FAQ

What is Claude Fable 5.1?

Claude Fable 5.1 is a model from Anthropic, with closed weights, used for text, agents.

How much does Claude Fable 5.1 cost?

On OpenRouter, US$ 10.00 per 1 million input tokens and US$ 50.00 per 1 million output tokens.

What is the context window of Claude Fable 5.1?

1,000,000 tokens, per OpenRouter.

Is Claude Fable 5.1 open source?

No. It is available through API only.

What is Claude Fable 5.1's GPQA Diamond (OpenRouter) score?

89.9% on GPQA Diamond (OpenRouter), per OpenRouter Benchmarks.

Is Claude Fable 5.1 good for coding?

No data: there is no SWE-bench Verified measurement for it in open sources.

Who made Claude Fable 5.1?

It was made by Anthropic, a lab from the US.

provisional data Questions under review: Semrush had no API balance during collection. Answers use source data only.

Models from Anthropic

See lab

Anthropic does not publish weights on Hugging Face: data only via OpenRouter and Epoch AI.

Sources

  • Epoch AI, CC BY 4.0, latest version we checked.
  • OpenRouter, dados públicos da API; exports de benchmarks e rankings em CC BY 4.0, latest version we checked.
  • OpenRouter Benchmarks, CC BY 4.0, latest version we checked.

Dates come from the sources: OpenRouter listing or Hugging Face repo creation, which may differ from the official launch. Family and version were grouped by rule from the name.